The peace treaties so laboriously concluded at Münster and Osnabrück in 1648 brought three European wars to an end. On 15 May, at a ceremony in the Münster town hall brilliantly recorded for posterity by the Dutch painter Gerard Terborch, the Eighty Years' War between the Spanish crown and its rebellious subjects in the northern Netherlands was formally brought to a close. The peace treaty between Spain and the Dutch Republic was followed on 6 August by the signing at Osnabrück of the terms of a preliminary settlement between Sweden and the Emperor Ferdinand III. Finally, on 24 October, again at Münster, the representatives of the Emperor and of Louis XIV, the young King of France, brought to an end the war declared in March 1636 by the Emperor's father, Ferdinand II, on Louis' father, Louis XIII. Collectively, these three treaties constituted what came to be known as the 'Peace of Westphalia'.

Three wars were effectively over, but Europe was still far from being a continent at peace. It would take another eleven years, and an immense amount of suffering on both sides, before the two leading European powers, France and Spain, settled their differences in 1659 at the Peace of the Pyrenees. Hostilities continued, too, in the Baltic region and eastern Europe, until 1660-1661, when Sweden made peace in turn with each of its enemies - Poland, Denmark and Russia. Yet although mid-century artists like Erasmus Quellinus in his Allegorie auf den Frieden (Münster, Stadtmuseum) might optimistically depict the return of peace, the black clouds of war were gathering again. Very soon the France of Louis XIV would be launching out on a round of aggression that would plunge large parts of the continent into another half-century of conflict.

Why, then, is the Peace of Westphalia celebrated as a defining moment in European history, and what did it actually achieve? The character of the peace settlement - its failures and successes - can only be properly appreciated through some understanding of the nature of the conflict that preceded it. This conflict was pan-European, and already in 1648, even before the ink was dry on the treaties, some people were calling it the 'Thirty Years' War'. In doing so, they looked back to the event that seemed to them to mark its opening - the revolt of the kingdom of Bohemia against the Emperor Matthias in 1618.

At the time, however, not everyone shared the same perspective on the events of the preceding decades. For the Dutch, hostilities effectively began in 1621, when their Twelve Years' Truce with Spain expired. As far as Spain was concerned, the Count-Duke of Olivares, the favourite and principal minister of Philip IV, warned the papal nuncio in 1629 that if French troops crossed the Alps to intervene in the dispute over the succession to the duchy of Mantua, this would be the beginning of a war with France that would last for thirty years. The peace settlement of the Pyrenees exactly thirty years later was to prove him an uncannily accurate prophet.

Yet the Thirty Years' War that entered the history books was the war of 1618-1648 which began, and ended, in the Holy Roman Empire. That war, however, for all its Imperial significance, was much more than a war within the Empire. It was in reality a European conflagration, and it was not only the German lands that were devastated by the murderous passage of armies on the move. But contemporaries were not mistaken in seeing the Empire as being at the heart of the conflict, nor in thinking that the spark generated by the Bohemian uprising had set the European tinder-box alight.

Why should an act of defiance by the Estates of Bohemia - vividly symbolized by the Defenestration of Prague on 23 May 1618 when two Catholic councillors and their secretary were hurled from the windows of the Hradschin but miraculously escaped with their lives - have precipitated a conflict of European dimensions?

Bohemia, with its four million inhabitants, in many ways epitomised the problems of the Holy Roman Empire of which it formed a part. The Bohemian question of the early seventeenth century was both political and religious. The Bohemian crown, although elective, was traditionally vested in the House of Habsbsurg, and in 1617 the ministers of the ageing and childless Emperor Matthias successfully induced the Bohemian Diet, followed by that of Hungary, to accept as his successor the Archduke Ferdinand of Styria, a member of the junior branch of the Austrian Habsburgs.

The imminent prospect of Ferdinand's succession as King of Bohemia and Hungary, and shortly thereafter as Holy Roman Emperor, was, however, a source of deep concern to many, both in Bohemia and Hungary, and also in the Austrian lands. Educated by the Jesuits at Ingolstadt, Ferdinand appeared the living image of the new dogmatic style of Counter-Reformation Catholicism which threatened to upset the precarious religious balance established in the Empire and the Habsburg patrimonial lands in the second half of the sixteenth century. These patrimonial lands contained many Protestants - in particular Lutherans and Calvinists - especially among the nobility. In Bohemia, where the religious confessions included the Brethren, whose doctrines went back to the days of John Hus, the Estates extracted from the Emperor Rudolf II in 1609 a 'Letter of Majesty', guaranteeing freedom of worship to all the faiths that had agreed to the Confessio Bohemica of 1575. But the strongest guarantee of all appeared to rest in the Estates or representative institutions of the various Habsburg territories. Protestant nobles were heavily represented in the aristocratic chambers of these Estates, and saw themselves as defenders of hard-won religious rights, as well as of the traditional laws and constitutional privileges of their respective kingdoms or provinces.

As the older, irenical, generation of political leaders in the Empire began to pass away around the turn of the sixteenth and seventeenth centuries, a new stridency was to be heard in Protestant as well as Catholic voices. As a revived and militant Counter-Reformation church began making deep inroads into Protestant communities, members of the reformed faiths felt increasingly insecure. They were also acutely suspicious of the political intentions of the new generation of Jesuit-educated Catholic princes like Duke Maximilian of Bavaria and the Archduke Ferdinand, who looked to their Jesuit confessors for political as well as religious advice. The deployment of Spanish power under Philip II, and the unremitting efforts of the Spanish army in Flanders to crush the revolt of the Netherlands, had long since led Protestants to equate Catholicism with tyranny and repression. The attitudes of a Maximilian or a Ferdinand, imbued with the conviction of their own righteousness as God's chosen agents for the redemption of the faith, could only reinforce the widespread Protestant belief that a concerted effort was under way not only to recatholicize the Empire, but also to extinguish political liberties wherever the Roman Church prevailed.

In order to halt the advancing tide of Counter-Reformation Catholicism, a Union of Protestant princes of the Empire was formed in 1608. Under Calvinist leadership, the Union became increasingly aggressive in its determination to resist what it saw as the growing menace of a revived Roman church supported by the massive power of Spain. It therefore began to explore the possibilities for the creation of a European anti-Habsburg alliance, to include the Dutch Republic, Venice, and Savoy under the government of its volatile duke, Charles Emmanuel. The Union also hoped for support from the England of James I.

As he observed these moves by the Union of Protestant princes, Spain's ambassador at the Imperial court, Don Baltasar de Zúñiga, grew increasingly alarmed at the passivity of the government of Philip III in Madrid. The necessity of a close working partnership between the Spanish and Austrian branches of the House of Austria was was taken as axiomatic at the Spanish court. As Zúñiga saw it, the pax hispanica that had uneasily prevailed in Europe since the turn of the century was now imperilled by a grand conspiracy being hatched by the enemies of the House of Austria, and Madrid would have to act fast if the Austrian Habsburgs were to be saved and central Europe rescued from the engulfing tide of heresy.

Although, to the enormous relief of Madrid, the problem of the succession to the Empire was successfully negotiated in 1617, the relief was to be short-lived. In the following year the pax hispanica was to be rudely shattered by the events in Bohemia. No sooner had the Bohemians agreed to the nomination of Ferdinand of Styria as king-designate, than they began to regret their decision. On moving his court from Prague to Vienna after the Diet was concluded, the Emperor left behind a group of regents, dominated by Catholics, who embarked on a number of provocative anti-Protestant measures. Tensions were rising rapidly as a Protestant assembly gathered in Prague at the beginning of May 1618, and on the 23rd the Protestants gave vent to their anger by defenestrating two of the regents. From then onwards events gained a momentum of their own, and none of the interested parties displayed any real interest in averting an armed confrontation.

The Bohemians turned to the Protestant Union for military help, while Ferdinand hastily assembled forces to reassert his authority over his troubled kingdom of Bohemia. Early in 1619 the moribund League of Catholic German princes was resurrected under the leadership of Maximilian of Bavaria for the defence of the Catholic cause in the Empire. In March of that year the Emperor Matthias died; and in August the seven electors of the Empire chose Ferdinand as his successor, under the title of the Emperor Ferdinand II. In the same month the Bohemian Estates formally deposed Ferdinand as their king, and offered the crown of Bohemia to a young and inexperienced Calvinist prince, the Elector Palatine Frederick V, the son-in-law of James I of England. After some initial hesitation, Frederick, encouraged by the news that an army led by the Prince of Translyvania, the Calvinist Behlen Gabor, was advancing into Habsurg Hungary, accepted the Bohemian offer.

What might, therefore, have looked at first sight like a local crisis possessed from the beginning much wider ramifications. With the alarm bells ringing across the continent, it appeared to Protestants and Catholics alike that the fate of their religions would be determined by the outcome of events in Bohemia. The German princes of the Empire found themselves being sucked into the Bohemian conflict, as members either of the Protestant Union or of the Catholic League. The Elector Palatine's acceptance of the Bohemian throne was a breach of the peace of the Empire, and an open challenge to the authority and preeminence of the House of Habsburg. The new Emperor, however, lacked the money and the troops to put down the rebellion, and he turned for help to the one source that could provide him with an ample supply of both - the Spain of Philip III.

The decision of Spain to come to the help of the Austrian branch of the Habsburgs did much to ensure the transformation of the Bohemian question into a generalized European conflict. The decision was not lightly taken. The Duke of Lerma, Philip III's favourite and chief minister, was well aware of Spain's financial problems, and was therefore cautious about becoming actively involved in the affairs of central Europe. But his hold on power was weakening, and the Spanish Council of State was increasingly dominated by Don Baltasar de Zúñiga, who had returned to Spain from Prague in 1617, and could speak with uncontested authority about the deteriorating situation in the Empire. With alarmist reports flowing in from his successor at the Imperial court, Zúñiga succeeded in persuading his colleagues that help must be sent to Vienna before it was too late. Spanish men and money therefore began reaching the Emperor in increasing quantities as Madrid made its bid to shore up the Imperial cause.

With Spain throwing off its inertia, 1620 was to be a year of notable Habsburg successes. In August, Ambrosio Spínola, the commander of the Spanish army of Flanders, invaded Frederick's homeland of the Rhenish Palatinate with 22,000 men, and soon gained control of the strategic Rhine valley. The same month, taking advantage of an uprising by the Catholic inhabitants of the Valtelline against their Protestant overlords, the Graubünden, Spanish forces from Milan occupied the vital Alpine pass linking Spanish Lombardy to the Habsburg Tyrol, and established a series of strong-points along the route used by Spanish regiments when marching northwards to the Netherlands by way of Alsace and Lorraine.

The most decisive of all the Habsburg victories of 1620 came on 8 November. Having secured mastery over Upper and Lower Austria, an army consisting of Imperial forces and those of the Catholic League under the command of the Count of Tilly crushingly defeated the Bohemian rebels not far from Prague, at the Battle of the White Mountain. His cause lost, Frederick and his wife - henceforth to be known as 'The Winter King and Queen' - fled the capital with their young children, eventually finding refuge in The Hague. Frederick would spend the remaining twelve years of his short and unsuccessful life seeking the support of Protestant princes for the recovery of his lands. The Bohemian revolt was over, the Habsburgs were victorious throughout their patrimonial lands, and Spanish forces had seized the occasion to consolidate their hold over the vital military corridors that ran from their bases in northern Italy to central Europe and the Netherlands.

Protestant Europe had every reason to be alarmed. In the fate of Bohemia it saw its own fate written in miniature. On the heels of the victorious Habsburgs came political repression. The estates of the Bohemian rebels were sequestered, and Ferdinand launched a systematic campaign to win the Czech lands back to Rome. Rudolf's Letter of Majesty was revoked, the Calvinists proscribed, and a reorganized Catholic church set out under Jesuit and Capuchin leadership to impose on Czech civilization a triumphalist Counter-Reformation culture. The Protestant Reformation throughout central Europe was now under threat. At the same time the victories of Spain and the Emperor had revived the terrifying spectre of Habsburg ambitions for Universal Monarchy, and of a Christendom dominated by the power of Spain and of Rome. The Protestant powers, which had signally failed to give effective support to the Elector Palatine, must somehow join forces to stem the Habsburg tide.

The world as seen from Madrid, however, looked very different. Although the situation in central Europe had been stabilized, and Spanish troops now controlled the Rhine valley and the Valtelline, an acute sense of vulnerability afflicted the Spanish ruling elite. With a world-wide empire to defend, military and naval costs were intolerably high. Resources had been depleted, the economy mismanaged, and fears were growing that the Spanish Empire, like the Roman Empire before it, was arriving at the point of irreversible decline. Everywhere Madrid looked, it saw its enemies poised to strike. Above all, it feared the Dutch, who had made use of the Twelve Years' Truce of 1609 to build up their power and prosperity at the expense of the Spanish economy and of Portugal's Asian empire, and were now taking the lead in the attempt to orchestrate an anti-Habsburg coalition.

The Twelve Years' Truce was due to expire in 1621, and throughout 1620 there was agonized debate in Madrid as to whether or not to renew it. From Brussels the cause of peace was being passionately argued by the Archdukes Albert and Isabella, whose government of the Spanish Netherlands as a semi-autonomous state within the monarquía española had laid the foundations for the creation of a brilliant Catholic civilization. But in Madrid there was a growing feeling, encouraged by the military successes of 1620, that the 1609 truce had been humiliating for Spain, and that the resumption of war in the Netherlands was the only way to hold the Dutch in check. In the Dutch Republic, too, a war party consisting of Calvinists and supporters of the House of Orange under the leadership of Prince Maurice of Nassau had seized the ascendancy. With a lack of will for peace in both Madrid and The Hague, the truce was doomed, and in April 1621 Spain and the Dutch were once again at war - a war that would only be terminated at Münster in 1648.

The resumption of war with the Dutch occurred in the opening days of the reign of the sixteen-year old Philip IV of Spain, whose father, Philip III, had died at the end of March. The new reign brought new ministers, and, with them, a new and more activist government than the one that had preceded it. Don Baltasar de Zúñiga, the advocate of support for the Emperor Ferdinand, became in effect the king's first minister, and was to hold this position until his death in October 1622; but behind the scenes Zúñiga's nephew, Don Gaspar de Guzmán, the Count (and later Count-Duke) of Olivares, was consolidating his hold on power as the favourite of the king. Zúñiga and Olivares, acting in collusion, were determined to restore the power and reputation of Spain, and ensure that the young Philip IV should assume what they saw as his rightful position as the greatest king in Europe.

At first sight it would seem that the activist policies of the new regime in Madrid were bound to lead to still further extensions of the war. But Zúñiga, with his long diplomatic experience in central and northern Europe, had a realistic appreciation of the problems facing Spain. He knew that the Dutch Republic was now too strong to be reduced by force of arms, and that the best that could be expected from the renewal of military activities in the Netherlands would be a peace settlement on terms less humiliating for Spain than those of 1609. He was also very anxious, now that the Habsburg position had been consolidated in Austria and Bohemia, that conflict in central Europe should be contained. All-out war between Protestants and Catholics in the Empire, which would inevitably involve the intervention of Spain in support of the Austrian Habsburgs, would place intolerable demands on the royal treasury, and would imperil the chances of economic revival in the Iberian peninsula.

Zúñiga's aspirations for the containment of the conflict - aspirations which Olivares would inherit - were not, however, to be realized. Wars once begun have a momentum of their own, and Madrid, while it controlled much, could not control everything. At the time when he was desperate for military assistance, the Emperor Ferdinand, in return for Maximilian of Bavaria's support, had rashly promised him Frederick's electoral title along with the Upper Palatinate, which was occupied by Bavarian troops in 1621. Maximilian now expected to have this pledge redeemed. The transfer of the title, however, was bound to provoke an uproar by upsetting the delicate religious balance in the Empire through the replacement of a Protestant by a Catholic elector. Ferdinand was thus caught between the demands of Maximilian and those of the princes of the Empire. He also faced opposition from Madrid, which feared that such a move would extend the war and involve Spain in conflict with the England of James I, which could hardly be expected to acquiesce in the permanent destitution of James's son-in-law through the loss of the Palatinate. Ferdinand resolved his dilemma by arranging in 1623 for the transfer to Maximilian of the electoral title, but only for his lifetime. The long-term future of Frederick's Palatine possessions was to be decided at a later date.

The deposition of Frederick and his dispossession from his lands could only sharpen the religious and political divisions across the continent. Although James I was not prepared to come to the aid of his son-in-law, whose folly he deplored, Frederick received assistance from the Dutch. He also had at his disposal an army commanded by Christian, Duke of Brunswick, and Ernest, Count of Mansfeld. Living by and for war, these two commanders were - like Tilly, the commander of the forces of the Catholic League - the new-style condottieri whose campaigns and counter-campaigns, fought with mercenary armies, were to ravage large parts of Germany and do so much to perpetuate the conflict. As the campaigns of the early 1620's were to demonstrate, war fed off war. Once the genie was released from the bottle, it was hard to put it back.

Among those to whom Frederick turned for help was Christian IV of Denmark. As a Protestant, and as a prince of the Empire in his capacity as Duke of Holstein, Christian had an obvious interest in developments in the German lands. Moreover, Denmark's traditional rivalry with Sweden made him anxious to extend his sphere of influence in Germany, in particular through the acquisition of secularized bishoprics, like that of Osnabrück, which would help him to secure control over the lucrative river trade of the Weser and the Elbe. After some hesitation he invaded Germany in 1625 as the self-proclaimed champion of the Protestant cause.

Denmark's costly intervention in the German conflict was to end in disaster in the following year. During the intervening period Ferdinand II had at last acquired what he had previously lacked - an army that he could call his own. This was raised for him by Albrecht von Wallenstein, a Czech noble who was to become the greatest military entrepreneur of the age. Suddenly confronted not only by the army of the Catholic League, commanded by Tilly, but also by the new Imperial army under Wallenstein, Christian found himself dangerously exposed. In August 1626 Tilly defeated him overwhelmingly at Lutter. Christian's participation in the German conflict was to peter out in humiliation, while Wallenstein moved the Imperial army northwards, to occupy the duchy of Mecklenburg and lay siege to the Hanseatic port city of Stralsund on the shores of the Baltic.

The abortive Danish intervention in Germany provides a good indication of how easily the conflict could escalate, and how, with each new escalation, the stakes were raised. As the Imperial and Catholic cause appeared to be sweeping everything before it, the Protestant camp was growing desperate, and began to look to another Protestant monarch from the north, Gustavus Adolphus of Sweden, to redress the balance before it was too late. Correspondingly, confidence was rising in the Habsburg capitals of Vienna and Madrid, where it increasingly seemed as if God favoured the cause of the House of Austria and would enable it to triumph.

Not only was the process of recatholicization under the Emperor's aegis gathering pace in Austria and the German lands, but the Spain of Philip IV won a series of notable victories in what was to be the annus mirabilis of the reign, 1625. These victories were to be commemorated ten years later in a series of battle paintings by Spanish and Italian artists commissioned for the great ceremonial hall, the Hall of Realms, in the palace of the Buen Retiro that Olivares constructed for Philip on the outskirts of Madrid in the 1630's. The run of Spanish victories was certainly impressive. During the course of 1625 a Spanish army rescued Spain's ally, the republic of Genoa, from a combined assault by the forces of France and Savoy; the English, who had now broken with Spain, were repulsed when they attacked Cadiz; and - in a transatlantic extension of the Spanish-Dutch conflict - a joint Spanish-Portuguese naval expedition drove the Dutch from Bahía in Portuguese Brazil. This last victory would be commemorated in the Hall of Realms by a brilliant painting by Juan Bautista Maino, in which the defeated Dutch kneel before a picture of the triumphant Philip IV who is crowned by Olivares with a wreath of laurels (Recapture of Bahía, Madrid, Prado).

But the most famous Spanish victory of that year also generated the most famous of the battle paintings: Velázquez's Surrender of Breda (Madrid, Prado). After enduring a prolonged siege, the strategic city of Breda in the Netherlands surrendered in June 1625 to the army of Flanders under the command of Ambrosio Spínola. Spínola is represented by Velázquez as the magnanimous victor placing a sympathetic hand on the shoulder of the defeated Justin of Nassau, who offers him the key to the fallen city. This idealized scene was a world away from the horrors and miseries of war graphically depicted in the engravings of Velázquez's French contemporary, Jacques Callot.

In his anxiety to capitalize on the successes of 1625 Olivares had a grandiose vision of bringing the Dutch to the negotiating table by breaking their grasp on the Baltic trade, the foundation of their prosperity. This would require the establishment of a Spanish naval base on the shores of the Baltic, and in Wallenstein - a man with visions as grandiose as his own - Olivares believed that he had found the perfect instrument for achieving his designs. The siege of Stralsund, undertaken by Wallenstein in 1628 with the Emperor's authorization, would provide Spain with its Baltic base for Olivares' grand design.

But Stralsund successfully withstood the attack of the Imperial army, and Wallenstein was compelled to withdraw. The failure of the siege of Stralsund was to prove a shattering blow to Spain and the Habsbsurg cause. It effectively put an end to Olivares' Baltic plans, and it did so at a moment when Spain was in growing trouble on another front and at another siege - the siege by Gonzalo Fernández de Córdoba, the commander of the Spanish army of Milan, of the fortress of Casale, in the north Italian marquisate of Montferrat.

Duke Vincent II of Mantua, an Imperial fief, had died in December 1627, leaving the succession to Mantua and Montferrat in dispute. The leading claimant was the French-born Charles of Gonzaga, Duke of Nevers, who moved fast to take over his new inheritance and omitted to go through the formalities of securing permission from the Emperor, as the suzerain lord of Mantua. Olivares was understandably worried by the prospect of a French dynasty establishing itself south of the Alps. He also saw in Nevers' precipitate action a unique opportunity to consolidate Spain's hold over the Lombard plain by acquiring the virtually impregnable fortress of Casale.

The Spanish military action in Italy in 1628 was bound to be seen in Paris as a challenge to the King of France, to whom Nevers turned for help when he found his inheritance contested. Hitherto, France had remained largely aloof from the conflicts raging elsewhere in Europe, although it had lent its support to Savoy against Genoa in 1625. Until Cardinal Richelieu became the principal minister of Louis XIII in 1624, French foreign policy had been hesitant and vacillating, and in his first years in power Richelieu had too many domestic preoccupations to give it firm and consistent direction. Although he was deeply convinced of the dangers posed to France by the successes of the House of Austria, he was under heavy pressure from the strong Catholic faction of the dévots to devote his energies to the suppression of Protestantism at home. Unless he could first prove his credentials to the dévots by tackling the problem of the religious and political challenge posed by the Huguenots, it would be hard for him to court the Protestant powers of Europe whose assistance was indispensable for the formation of a grand anti-Habsurg coalition.

The resolution of the Huguenot question therefore became Richelieu's first priority. The Huguenot bastion of La Rochelle was a continual reminder to the French crown that it was not fully the master in its own house, and in 1627, under the active direction of Louis XIII and Richelieu, the royal army set out to besiege it. Three great sieges, therefore, were simultaneously under way in Europe in 1628 - at Stralsund, Casale, and La Rochelle. The outcome of these sieges would do much to determine the fate of seventeenth-century Europe. The failure of Wallenstein at Stralsund not only wrecked Spain's grand design against the Dutch, but also brought Gustavus Adolphus' intervention in the German conflict appreciably closer because of the direct challenge posed by Wallenstein's military operations to Sweden's aspirations to supremacy in the Baltic. The inability of Gonzalo de Córdoba throughout 1628 to reduce Casale to surrender placed enormous additional strains on Spain's already overstretched resources, and gave the Dutch an opportunity to recover the initiative in their struggle against the Spanish army of Flanders. When in September 1628, in a daring attack on the Cuban harbour of Matanzas, the Dutch privateer, Piet Heyn, captured the treasure fleet bringing back the annual consignment of American silver to Spain, Madrid was faced with the stark question of whether it could afford to sustain costly campaigns simultaneously in Italy and Flanders, while also sending annual subsidies for the support of the Emperor.

While the siege of Stralsund failed, and the siege of Casale flagged, that of La Rochelle moved slowly but relentlessly towards a successful conclusion. On 28 October 1628 the city surrendered to Louis XIII, and, for the first time in his four years of power, Richelieu at last had some room for manoeuvre. Olivares reckoned that there would still be time for Gonzalo de Córdoba to capture Casale before France would be in a position to intervene in Italy on behalf of the Duke of Nevers, but once again he miscalculated. To Madrid's amazement, Louis XIII led his army across the Alps through heavy snows at the end of February 1629. Charles Emmanuel of Savoy, who had hoped to partition Montferrat with Spain, struck a hasty deal with the French, and Gonzalo de Córdoba had no choice but to raise the siege of Casale.

The War of the Mantuan Succession, which lasted from 1628-31, was to prove a disaster for Olivares' grand strategy. Although the situation in Mantua was eventually saved for the Habsburgs by the intervention of the Imperial army, this was achieved at a heavy cost. The close relationship between the Austrian and Spanish Habsburgs, which was critical to the long-term success of the Count-Duke's strategy, was seriously strained as the different priorities of Madrid and Vienna became increasingly apparent. Ferdinand II, advised by his Jesuit confessor, Lamormaini, was anxious to press ahead with his programme of recatholicization in the German lands. In 1629, to the dismay of Madrid, he issued his famous Edict of Restitution. Since this sought to impose a religious settlement that excluded the Calvinists and involved a massive restoration to their former owners of the church of properties which had fallen into secular hands, the Edict could only extend and prolong the conflict in Germany, at a time when Spain needed the Emperor's help in Italy. Although the Emperor finally acceded to Madrid's urgent request for military help in Italy, the diversion of the Imperial forces to the Mantuan War effectively ended all possibility of a combined Spanish-Imperial attack on the Dutch, and with it the Count-Duke's hopes of securing peace with the Dutch Republic on better terms than those of 1609.

Above all, as Olivares predicted, the French intervention in Mantua presaged all-out war between France and Spain, not least because the French contrived to retain a stronghold south of the Alps, the fortess of Pinerolo. But for the time being, neither party was ready for war, and the Mantuan conflict was therefore contained. Richelieu still needed to consolidate his position at home, and preferred instead to bide his time and find surrogates to do his fighting for him, while patiently laying the diplomatic groundwork for the anti-Habsburg coalition without which there could be no prospect of a successful war against the encircling power of Spain.

France had already been subsidizing the Dutch Republic since 1624, and in 1630 the subsidy arrangements were renewed. In the Empire, where the German princes - Catholic and Protestant alike - were increasingly alarmed by the growth of Imperial power and by Ferdinand's religious intransigence, French diplomacy engaged in a difficult balancing act as it sought to make overtures to Maximilian of Bavaria and the Catholic League without alienating the Protestants. But Richelieu's immediate hope was to enlist the formidable military power of Sweden in the anti-Habsburg cause. The essential preliminary to this was peace between Sweden and Poland, which France helped to broker in 1629. Gustavus Adolphus now knew that he could count on French financial support if he decided to intervene in the conflict. In late June 1630 he landed with his troops at Peenemünde - appropriately in the midst of a thunderstorm.

The military intervention of Sweden in Germany meant the unleashing on German soil of a powerful and disciplined war-machine led by a commander of genius. The purpose of Gustavus Adolphus' intervention seems at first to have been limited. Offended by Spain's Baltic ambitions he wanted to clear hostile forces out of northern Germany, restore the pre-war status quo in the region, and establish a naval base on the German shore which would help to ensure security and freeedom of trade in the Baltic. But, as with so many other participants in the struggle, each new advance brought with it new involvements, and for Gustavus there was to be no turning back as he was hailed throughout anti-Habsburg Europe as the champion both of 'German liberties' and the Protestant cause.

Gustavus had timed his invasion of Pomerania well. The German princes had been seeking to clip the Emperor's wings by securing the removal of Wallenstein, and only a few weeks after the Swedish descent on Germany Ferdinand felt compelled to dismiss the general who had brought such triumphs to the Habsburg cause. Those parts of the Imperial army which were not still in Mantua were merged with forces of the Catholic League under the command of Tilly, and the combined forces laid siege to the staunchly Protestant city of Magdeburg which had defied the Emperor and come out in support of Gustavus. The Swedes were unable to break through in time to save their ally. On 20 May 1631, after suffering the most terrible privations, Magdeburg surrendered; and, in what was to be one of the most emblematic events of the Thirty Years' War, the Imperial forces ransacked, looted and destroyed the city, massacring a large proportion of its 20,000 inhabitants.

The destruction of Magdeburg - graphically described and illustrated in the broadsheets and newsletters which kept readers across the continent informed of the course of the war - sent shock-waves through Protestant Europe, which now turned to Gustavus Adolphus and his Swedes as its only hope of salvation. In June 1631 George William, the Elector of Brandenburg and the effective leader of the German Calvinists, threw in his lot with the Swedish king. Three months later his Lutheran rival, John George of Saxony, seeing his electorate threated by Tilly's army, followed suit. With the support of his German Protestant allies Gustavus won a great victory over Tilly at Breitenfeld on 17 September, and the 1632 campaigning season was to bring him further triumphs. In the early spring Tilly was killed and his army routed at Rain in Bavaria. In May, Gustavus Adolphus, accompanied by Frederick the Elector Palatine, made a triumphal entry into Maximilian's capital of Munich, and Protestant forces laid waste his duchy.

With Vienna itself now threatened, Ferdinand turned in desperation to Wallenstein, recalling him from his retirement to raise and lead a new Imperial army, in a last bid to save the Habsburg cause. On 16 November 1632 the armies of Gustavus and Wallenstein faced each other at Lützen. Although the Imperialists had the worst of the ensuing battle, the Swedes suffered an irreparable loss. When the confusion of battle lifted, Gustavus was among the dead.

In his two meteoric years of campaigning in the Empire Gustavus Adolphus had transformed the course of the war. The Swedish intervention effectively turned all Germany into a battleground, bringing death and destruction to great stretches of teritory, as in Bavaria, which had previously escaped unscathed. It also saved the Protestant cause at a critical moment in its fortunes, and, with it, the liberties of the German princes who felt themselves threatened by the revival of Imperial power. Yet although Protestant Europe had now lost its saviour, the Swedes still remained a formidable presence, thanks in particular to the skills of Gustavus Adolphus's Chancellor, Axel Oxenstierna, who became head of the regency government of Sweden's new monarch, the six-year-old Queen Christina. But the costs of maintaining a large Swedish army in the Empire were formidable, and not even Oxenstierna's diplomatic skills could hold his German allies in line.

Wallenstein seized the opportunity afforded him by Gustavus Adolphus' death to move over to the offensive. Simultaneously the Duke of Feria, the Spanish governor of Milan, assembled a large Spanish army, which marched northwards in the summer of 1633 to restore the Habsburg position in southern Germany and reopen the military corridors between Milan and Brussels. These had been blocked or imperilled by the Swedish victories, and their reopening was vital for the successful prosecution of the war in the Netherlands.

Everywhere war-weariness was growing, and the only hope of peace seemed to lie in a reconciliation between the German princes and Ferdinand II. But as long as the Imperial army was commanded by Wallenstein, reconciliation was out of the question. In recent years Wallenstein's behaviour had become so bizarre that his intentions were arousing profound suspicions, not least at the Imperial court, where his many enemies included the Emperor's son and heir, Ferdinand, King of Hungary. Although Madrid could not believe that Wallenstein was contemplating treachery, the Emperor, encouraged by Lamormaini, was finally persuaded that his dangerously powerful vassal was conspiring to seize power in the Habsburg lands for himself, and decided for the second time that he must be removed from his command. On 25 February 1634, a month after Ferdinand reached his decision, Wallenstein was assassinated in the castle at Eger to which he had fled when he realized that his army was abandoning him.

The Wallenstein drama drove home once again the dangers for monarchs of becoming excessively dependent on the great condottieri thrown up by the war. Armies raised and commanded by semi-independent satraps were all too likely to be armies out of control. Following the dismissal and death of Wallenstein, the Imperial army was placed under the command of Ferdinand of Hungary, the Emperor's son. But the Emperor lacked the money to pay for his army, and depended on Madrid for subsidies; and Madrid for its part used the subsidies as bargaining counters at the Imperial court, to secure Imperial collaboration in Spain's grand strategy for the prosecution of the war against the Dutch.

At the end of December 1633 the Infanta Isabella died in Brussels, having outlived the Archduke Albert by twelve years. Philip IV had already chosen his vigorous younger brother Ferdinand, the Cardinal-Infante, to succeed her in the government of the Spanish Netherlands. It was decided that, following up the initial successes won by the Duke of Feria's 1633 campaign, the Cardinal-Infante should be placed at the head of another powerful army of Spaniards and Italians assembled in Milan, and march northwards to take up his governorship of the Netherlands. En route he would effect a junction with the Imperial army, and the two armies would clear southern Germany of the Habsburgs' enemies before the Cardinal-Infante resumed his northern march, reopening as he went the 'Spanish road' running from Milan to Brussels.

The two armies linked up in September 1634 outside the Protestant city of Nördlingen, which Ferdinand of Hungary was besieging - a scene that was to be depicted by Rubens in his great painting of The Meeting of Ferdinand King of Hungary and the Cardinal-Infante Ferdinand at Nördlingen (Vienna, Kunsthistorisches Museum). On 6 September at Nördlingen the Habsburg forces, 33,000 men strong, gained a massive victory over the 25,000 Swedes and Germans commanded respectively by Oxenstierna's son-in-law, Gustav Horn, and the Lutheran Duke Bernard of Saxe-Weimar. Bernard was already in receipt of French pay, and in the following year he transferred his allegiance, and that of his army, from Sweden to France.

Nördlingen - 'the greatest victory of our times' as Olivares called it - offered impressive proof of the continuing military power of Spain. All southern Germany was occupied by the victors, and Sweden's allies among the north German princes were thrown into disarray. Since French forces were stationed in Alsace and at key points along the Rhine, the Spanish road could not be fully cleared without precipitating open war with France. But, escorted by one of the more prominent Spanish commanders of the period, the Marquis of Leganés (P.P.Rubens, Marquis of Leganés, Vienna, Graphische Sammlung, Albertina), the Cardinal-Infante moved inexorably northwards and entered Brussels in triumph on 4 November 1634.

While Olivares was anxious to exploit the Habsburg victory at Nördlingen to establish a formal League of Alliance between Vienna and Madrid for operations against the Dutch, and perhaps also one day against the French, the Emperor and the King of Hungary were more concerned to take advantage of the new and more favourable balance of forces in Germany to restore peace in the Empire. This would mean concessions to the Protestants over the Edict of Restitution - concessions to which Lamormaini remained bitterly opposed. But the Emperor's confessor and confidant lost his battle with the the more moderate privy councillors at the Imperial court. In order to win over the more conservative Protestant princes, like the Elector of Saxony, it would be necessary to abandon Lamormaini's militant Catholic programme. On 30 May 1635 Imperial and Saxon delegates signed the Peace of Prague, to which Brandenburg also decided to adhere three months later.

The Peace of Prague, welcomed with jubilation on the streets of Vienna, could not restore full peace to the Empire, and still less to Europe as a whole. But it represented an important step on the road to reconciliation in Germany, because the abandonment of the aggressive Counter-Reformation policies pursued by Ferdinand II since the beginning of his reign did much to reduce the confessional and ideological tensions which had kept passions running so high in the Empire since the early years of the seventeenth century. Effectively, the underlying principle of the Augsburg settlement of 1555 - the agreement to disagree on questions of religion - was now renewed. The return to these more moderate and conciliatory policies in the Empire would point the way to the peace settlement of Westphalia in 1648.

The triumph of the moderates at the Imperial court also had immediate consequences for the internal political arrangements of the Empire. Ferdinand, King of Hungary, was duly elected King of the Romans at the Electoral Convention of Regensburg in December 1636, and the way was thus prepared for his smooth succession as the Emperor Ferdinand III following the death of his father early in 1637. Ferdinand II's death symbolized as well as anything the demise of the age of confessional politics in the Europe of the seventeenth century.

Although Nördlingen enhanced the prospects for peace in the Empire, it also presaged a dramatic widening of the wider, European, struggle. The defeat of the Swedes and the apparently overwhelming military superiority achieved by the Habsburgs meant that Richelieu could no longer play his waiting game. France would now have to show its hand openly, and intervene on the side of the Dutch, the Swedes and the dissident German princes, as the leader of a Catholic and Protestant anti-Habsburg coalition designed to save Europe from domination by Spain. In order to appeal to European public opinion, Richelieu set his publicity machine in motion, and Olivares responded in kind for Spain. On 19 May 1635, after the Cardinal had concluded formal alliances with the Swedes and the Dutch, a French herald arrived in Brussels to proclaim the official opening of hostilities between the crowns of France and Spain.

The Cardinal-Infante refused to receive the herald, who was reduced to throwing down a copy of the declaration in the streets of Brussels and posting another on the frontier between France and the Spanish Netherlands. It was obviously easier to make war in seventeenth-century Europe than declare it. But the farcical character of these proceedings belied the gravity of the conflict that was now opening - a twenty-four year conflict between the two greatest powers in Europe, France and Spain, for continental hegemony. If the conflict was to end in victory for France, this was by no means apparent in 1635.

The resources of both powers were, from the beginning, heavily stretched. France's geographical position gave it obvious logistical advantages, including the possibility of striking with relative rapidity against the Spanish Netherlands, or of moving military contingents across the Rhine, the Alps and the Pyrenees. But it was hard to raise men and money in a country with so many provincial and corporate privileges, and Richelieu, faced with widespread resistance to the implementing of the king's orders, encountered endless difficulties in mobilizing his country for war. Olivares faced very similar problems, but Spain had been on a war footing for longer, its formidable military machine was more experienced and better prepared, and Madrid could still count on regular remittances of silver from the viceroyalties of Mexico and Peru to help keep its armies in the field.

The advantage in the opening years of the war in fact lay with Spain, which received the formal support of the Austrian Habsburgs when the Emperor issued a declaration of war against France in March 1636. In August of that year the Cardinal Infante's forces, together with units of the Imperial army, advanced as far as Corbie, little more than a hundred kilometers from Paris. For a moment it seemed to Richelieu that everything was lost. But Spanish power, deployed simultaneously against France and the Dutch Republic, was overstretched, and in October 1637 the Spaniards received a terrible blow to their pride when the forces of Frederick Henry, Maurice of Nassau's successor as the Dutch Stadholder, recaptured Breda. Breda fell at a moment when the paint was still fresh on Velázquez's canvas depicting its surrender to Spínola in 1625.

The strains imposed by the war on both France and Spain were so great that it was an open question as to which of the two powers would be the first to break. In a bid to restore peace to Europe Pope Urban VIII attempted to arrange a peace congress at Cologne in October 1636, but was rebuffed by the interested parties, none of which trusted his impartiality. Richelieu and Olivares, however, began covert peace negotiations of their own at an early stage of the conflict, and in 1638 were arranging for an exchange of each other's portraits as a testimonial of mutual goodwill (Velázquez, The Count-Duke of Olivares, St.Petersburg, Hermitage). But although the negotiations continued fitfully, the two parties were constantly changing their terms for a settlement in the light of the fluctuating fortunes of war; and since both the Count-Duke and the Cardinal talked of 'peace with honour', and still hoped for out-right victory, peace remained beyond their grasp.

In 1639-40, however, the balance of war began to tilt in favour of the anti-Habsburg coalition. When Bernard of Saxe-Weimar captured Breisach at the end of 1638 the military corridor from Milan to the Netherlands was once again cut. The alternative was to send men and supplies from Spain to Flanders by sea. In October 1639 a great Spanish armada making its way through the English Channel with reinforcements for the Cardinal-Infante's army was destroyed by the Dutch at the Battle of the Downs off the coast of England, where the government of Charles I had opted for a prudent, if pro-Spanish, neutrality. The destruction of this fleet was a devastating blow to Spanish naval power, and left the Spanish army of Flanders dangerously exposed to Dutch and French attacks.

The year 1640 was to be a year of disaster for Spain. French military probes across the Pyrenees into Catalan territory had aggravated the tensions that had long existed between the principality of Catalonia and the government of Olivares in Madrid, which had been insistently demanding more help from the Catalans for the war against France. In the spring and summer of 1640 armed rebellion, begun by an exasperated peasantry, spread like wildfire across the Catalan countryside. Six months later the Catalan authorities, in exchange for French military assistance, formally ended Catalonia's allegiance to Philip IV and transfered it to Louis XIII.

The success of the Catalans in defying Madrid provided the opportunity for another restless people, on the other side of the Iberian peninsula, to follow suit. Portugal had been uneasily yoked to Spain since the union of the crowns in 1580. Five years after their defeat at Bahía in 1625 the Dutch began returning to Brazil. With the failure in early 1640 of yet another Spanish naval expedition to dislodge them, the perceived advantages of the union to Portugal were rapidly diminishing. Spain, it seemed, was incapable of protecting Portugal's overseas possessions. On 1 December 1640 a brilliantly planned coup d'état in Lisbon overthrew the Spanish viceroyalty, and transformed the Duke of Braganza, who could claim descent from the Portuguese royal line, into King John IV of a newly restored and independent kingdom of Portugal.

Aready in late 1640, before the coup d'état in Lisbon, Olivares had written: 'In many centuries there cannot have been a more unlucky year than the present one...I propose peace and more peace...' Although he made heroic efforts to repair the damage, with two simultaneous rebellions in the Iberian peninsula the game was as good as lost. In January 1643 Philip IV gave the man who for twenty-two years had directed the fortunes of Spain formal permission to retire from office. The Count-Duke's fall from power came little more than a month after the death of his rival, Richelieu. By the time of his death the Cardinal could at least sense that he had set his country on the road to victory.

As if to set the seal on Richelieu's work, the French inflicted a crushing defeat on Spain's army of Flanders at the battle of Rocroi in May 1643. With the 'Spanish road' now cut in several places and the English Channel blocked by the Dutch, Spanish forces in the Netherlands, deprived of men and money, were driven onto the defensive, and were in no position to launch further invasions of France. But in France, too, the war effort was taking its toll. Louis XIII survived the Cardinal by only six months. His death in May 1643 meant a regency government for his five-year-old son, Louis XIV, headed by his widow, Anne of Austria, the sister of Philip IV. The country was restless and war-weary, and Richelieu's chosen successor, the Italian-born Cardinal Mazarin, a former papal diplomat in the service of Urban VIII, was very conscious of the pressures for peace.

With Spain and France both faltering, the German lands still ravaged by marauding war bands, and war-weariness intense across the continent from Sweden to northern Italy and Spain, the time seemed appropriate for a new peace initiative. Ever since 1634 Urban VIII had been proposing the summoning of a European congress to resolve the disputes between the warring parties, and in the winter of 1641 the Emperor had accepted a proposal made by the French and the Swedes that two congresses should be summoned simultaneously in Westphalia, with representatives of the Catholic states meeting in Münster and of the Protestant states in Osnabrück. Although the clamour for peace - expressed in pamphlets, broadsheets and sermons - was becoming irresistible, there were still to be endless delays while the potential participants manoeuvred to strengthen their bargaining positions. As a result, it was only in the later summer and early autumn of 1645 that serious negotiations began in Westphalia.

Eventually 176 plenipotentiaries, representing 194 rulers, assembled either in Münster or in Osnabrück. Discussions might have proceeded more rapidly if the peace conference had been attended by heads of state or senior ministers, but the delegates - almost half of them lawyers - were no more than ambassadors, who continually had to report back to their masters, and wait for new instructions. It is not therefore surprising that negotiations proved long and arduous, with rulers constantly changing their positions as they gained or lost ground in the latest military campaign.

Although this was a European congress the essential preliminary for achieving a general European settlement was the achievement of peace in the Empire. As the chief Imperial negotiator, Count Trauttmannsdorf, appreciated, this would require major concessions by all the leading participants in the conflict, including the Emperor. One consistent obstacle to peace in the Empire had been the unresolved problem of the Palatinate. Maximilian of Bavaria had no intention of abandoning his electoral dignity or the Upper Palatinate, and the Emperor was in no position to dislodge him. In the end he was confirmed in his electoral title as an additional, eighth, Elector to the Empire. He kept the Upper Palatinate, too, while Charles Louis, the son of Frederick V, was restored to the Rhenish Palatinate only. A second major territorial obstacle to peace in the Empire was the fate of Pomerania, which the Swedes had occupied, but to which they had no legal entitlement. In 1647 Sweden reluctantly agreed to the partition of Pomerania, ceding the eastern portion to the Elector of Brandenburg.

There remained the question of a religious settlement, and here it was possible to build on, and refine, the agreements reached in the Peace of Prague in 1635. In a victory for the Protestant princes, the Emperor revoked the Edict of Restitution, the normative date for fixing all religious changes was pushed back at their insistence from 1627 to 1624, and the Calvinists, who had been excluded from the Augusburg settlement of 1555, were now at last included. The new settlement was reached by the negotiating parties without reference to the wishes of Urban VIII's successor, Pope Innocent X. It confirmed in perpetuity the religious fragmentation of the Empire based on the acceptance of confessional differences. It also confirmed the definitive constitution of the Empire as a federalist structure, with its own machinery of arbitration to settle disputes among its members.

Underlying all the negotiations at Münster and Osnabrück was the determination of France and Spain, in the event of being unable to reach a mutual understanding, to detach each other from their principal allies. This meant that French diplomacy was working to break the traditional alliance between Vienna and Madrid by securing peace with the Emperor, while Spanish diplomacy sought to reduce Spain's military burdens by detaching the Dutch from the French.

Spain and the Dutch Republic had made tentative approaches to each other during the 1630's, but one of the major stumbling-blocks to a settlement had been the presence of the Dutch in Brazil. Although it was not immediately apparent at the time, Portugal's recovery of independence in 1640 had the effect of removing this impediment to peace. While Philip IV had no intention of resigning himself to the permanent loss of Portugal, the dislodging of the Dutch from Brazil, which had declared its allegiance to the Duke of Braganza, had ceased to be a Spanish priority. On this basis it was possible to resume discussions. Spain was in desperate straits, with campaigns being conducted simultaneously in the east and west of the peninsula for the recovery of Catalonia and Portugal, and the outbreak in 1647 of further revolts, this time in the Spanish viceroyalties of Naples and Sicily. Spain's plenipotentiary at Westphalia, the Count of Peñaranda, played his cards as skilfully as was possible in the circumstances, and succeeded in negotiating a settlement with the Dutch, who were becoming concerned by the prospect of an excessively powerful France on their doorstep. In return for peace, Spain formally acknowledged what had long been an established fact - the existence of an independent Dutch Republic. Madrid was also forced to recognize Dutch conquests in the East and West Indies. In return the Dutch had to accept that they would not be allowed direct access to trade with Spain's American possessions. On 30 January 1648 the seventy-nine articles of the settlement were signed on behalf of the King of Spain and the States General in the town hall of Münster.

Having lost his Dutch ally, Mazarin was now all the more anxious to divide the Austrian from Spanish Habsburgs by negotiating peace with the Emperor. With the outbreak of the revolt of the Fronde in Paris, these were perilous days in France, both for Mazarin and the monarchy. But if Mazarin was under pressure, so too was Ferdinand III. In July 1648 the Swedes again reached Prague, looting the Imperial collections and sending their booty back to Stockholm. To forestall further disaster, the Emperor agreed to a draft peace settlement with the Swedes at Osnabrück in August. The same month the French won a great victory at Lens over the army of Flanders under the command of Ferdinand's brother, the Archduke Leopold William, who had recently been appointed governor of the Spanish Netherlands. The Emperor suffered from terrible scruples about abandoning his brother-in-law, Philip IV of Spain, but at the treaty signed between France and the Emperor at Münster on 24 October 1648 political and military realities prevailed over family loyalties.

France and Spain, now deprived of their leading allies, but equally freed from the burden of dangerous enemies, chose to continue their war rather than accept a settlement which would require painful concessions by both sides. Nothing less was at stake than hegemony in Europe, and with France in turmoil, Spain still cherished hopes of redresssing the balance that had tilted so heavily against it since 1640. But, even if the Franco-Spanish war was to continue for another eleven years, the lineaments of a new Europe were already becoming apparent.

This Europe, as shaped by the Peace of Westphalia, was to be a continent in which the secular interests of states were to be of more importance in the conduct of international affairs than their religious differences. In this more secularized continent, the papacy, which had been relegated to the sidelines in the Westphalia negotiations, ceased to be even the nominal arbitrator of Christendom. Indeed, it was a symptom of the changing times that the very term 'Christendom' was more and more to yield pride of place to 'Europe'.

The underlying principle on which the new European order of the post-Westphalia years was to be constructed was the principle of religious and political diversity. The recognition of diversity ran through the settlement in the Empire, and triumphed in the recognition of an independent Dutch Republic. Spain failed to impose its political and religious programme on the Dutch, just as the Emperor failed to impose his political and religious programme on the Empire. His failure would encourage his successors to turn their attention away from Germany to the Habsburg patrimonial lands, and devote their energies to the construction of what would in due course become the Austro-Hungarian monarchy.

For thirty years, war between competing states and religious faiths had not only ravaged the continent, but had even reached across the Atlantic to the West Indies and Brazil. When peace arrived in 1648 it was fragile and incomplete. But it proved resilient and enduring enough to bring stability to the Empire, and to make possible, at least in parts of a war-torn Europe - although not in the Czech lands where it all began - the hesitant growth of political liberty and religious tolerance.