Thirty Years' War - Origins of The War

Origins of The War

The Peace of Augsburg (1555), signed by Charles V, Holy Roman Emperor, confirmed the result of the 1526 Diet of Speyer, ending the war between German Lutherans and Catholics, and establishing that:

• Rulers of the 224 German states could choose the religion (Lutheranism or Catholicism) of their realms according to their consciences, and compel their subjects to follow that faith (the principle of cuius regio, eius religio).
• Lutherans living in a prince-bishopric (a state ruled by a Catholic bishop) could continue to practice their faith.
• Lutherans could keep the territory they had captured from the Catholic Church since the Peace of Passau in 1552.
• Those prince-bishops who had converted to Lutheranism were required to give up their territories (the principle called reservatum ecclesiasticum).

Although the Peace of Augsburg created a temporary end to hostilities, it did not resolve the underlying religious conflict, which was made yet more complex by the spread of Calvinism throughout Germany in the years that followed. This added a third major faith to the region, but its position was not recognized in any way by the Augsburg terms, to which only Catholicism and Lutheranism were parties.

The rulers of the nations neighboring the Holy Roman Empire also contributed to the outbreak of the Thirty Years' War:

• Spain was interested in the German states because it held the territories of the Spanish Netherlands in the western part of the Empire and states within Italy which were connected by land through the Spanish Road. The Dutch revolted against the Spanish domination during the 1560s, leading to a protracted war of independence that led to a truce only in 1609.
• France was nearly surrounded by territory controlled by the two Habsburg states (Spain and the Holy Roman Empire), and was eager to exert its power against the weaker German states; this dynastic concern overtook religious ones and led to Catholic France's participation on the otherwise Protestant side of the war.
• Sweden and Denmark were interested in gaining control over northern German states bordering the Baltic Sea.

The Holy Roman Empire was a fragmented collection of largely independent states. The position of the Holy Roman Emperor was mainly titular, but the emperors, from the House of Habsburg, also directly ruled a large portion of Imperial territory (the Archduchy of Austria, as well as Kingdom of Bohemia and Kingdom of Hungary). The Austrian domain was thus a major European power in its own right, ruling over some eight million subjects. The House of Habsburg, under a second King, also ruled Spain, including the Spanish Netherlands, south Italy, the Phillipines and most of the Americas. The Empire also contained several regional powers, such as the Duchy of Bavaria, the Electorate of Saxony, the Margraviate of Brandenburg, the Electorate of the Palatinate, Landgraviate of Hesse, the Archbishopric of Trier and the Free Imperial City of Nuremberg (containing from 500,000 to one million inhabitants). A vast number of minor independent duchies, free cities, abbeys, prince-bishoprics, and petty lordships (whose authority sometimes extended to no more than a single village) rounded out the Empire. Apart from Austria and perhaps Bavaria, none of those entities was capable of national-level politics; alliances between family-related states were common, due partly to the frequent practice of splitting a lord's inheritance among the various sons.

Religious tensions remained strong throughout the second half of the 16th century. The Peace of Augsburg began to unravel, as some converted bishops refused to give up their bishoprics, and as certain Habsburg and other Catholic rulers of the Holy Roman Empire and Spain sought to restore the power of Catholicism in the region. This was evident from the Cologne War (1583–88), a conflict initiated when the prince-archbishop of the city, Gebhard Truchsess von Waldburg, converted to Calvinism. As he was an imperial elector, this could have produced a Protestant majority in the College that elected the Holy Roman Emperor – a position that had always been held by a Catholic.

In the Cologne War, Spanish troops expelled the former prince-archbishop and replaced him with Ernst of Bavaria, a Roman Catholic. After this success, the Catholics regained peace, and the principle of cuius regio, eius religio began to be exerted more strictly in Bavaria, Würzburg and other states. This forced Lutheran residents to choose between conversion or exile. Lutherans also witnessed the defection of the lords of the Palatinate (1560), Nassau (1578), Hesse-Kassel (1603) and Brandenburg (1613) to the new Calvinist faith. Thus, at the beginning of the 17th century, the Rhine lands and those south to the Danube were largely Catholic, while Lutherans predominated in the north, and Calvinists dominated in certain other areas, such as west-central Germany, Switzerland and the Netherlands. However, minorities of each creed existed almost everywhere. In some lordships and cities, the number of Calvinists, Catholics, and Lutherans were approximately equal.

Much to the consternation of their Spanish ruling cousins, the Habsburg emperors who followed Charles V (especially Ferdinand I and Maximilian II, but also Rudolf II, and his successor Matthias) were content for the princes of the Empire to choose their own religious policies. These rulers avoided religious wars within the empire by allowing the different Christian faiths to spread without coercion. This angered those who sought religious uniformity. Meanwhile, Sweden and Denmark, both Lutheran kingdoms, sought to assist the Protestant cause in the Empire, and wanted to gain political and economic influence there as well.

Religious tensions broke into violence in the German free city of Donauwörth in 1606. There, the Lutheran majority barred the Catholic residents of the Swabian town from holding an annual Markus procession, which provoked a riot. This prompted foreign intervention by Duke Maximilian of Bavaria (1573–1651) on behalf of the Catholics. After the violence ceased, Calvinists in Germany (who remained a minority) felt the most threatened. They banded together and formed the League of Evangelical Union in 1608, under the leadership of the Elector Palatine Frederick IV (1583–1610), (whose son, Frederick V, married Elizabeth Stuart, the daughter of James I of England). The establishment of the League prompted the Catholics into banding together to form the Catholic League in 1609, under the leadership of Duke Maximilian.

Tensions escalated further in 1609, with the War of the Jülich succession, which began when John William, Duke of Jülich-Cleves-Berg, the ruler of the strategically important United Duchies of Jülich-Cleves-Berg, died childless. There were two rival claimants to the duchy. The first was Duchess Anna of Prussia, daughter of Duke John William's eldest sister, Marie Eleonore of Cleves. Anna was married to John Sigismund, Elector of Brandenburg. The second was Wolfgang William, Count Palatine of Neuburg, who was the son of Duke John William's second eldest sister, Anna of Cleves. Duchess Anna of Prussia claimed Jülich-Cleves-Berg as the heir to the senior line, while Wolfgang William, Count Palatine of Neuburg claimed Jülich-Cleves-Berg as Duke John William's eldest male heir. Both claimants were Protestants. In 1610, to prevent war between the rival claimants, the forces of Rudolf II, Holy Roman Emperor occupied Jülich-Cleves-Berg until the dispute was decided by the Aulic Council (Reichshofrat). However, several Protestant princes feared the Emperor, a devout Catholic, intended to keep Jülich-Cleves-Berg for himself to prevent the United Duchies falling into Protestant hands. Representatives of Henry IV of France and the Dutch Republic gathered forces to invade Jülich-Cleves-Berg, but these plans were cut short by the assassination of Henry IV. Hoping to gain an advantage in the dispute, Wolfgang William converted to Catholicism; John Sigismund, on the other hand, converted to Calvinism (although Anna of Prussia stayed Lutheran). The dispute was settled in 1614 with the Treaty of Xanten, by which the United Duchies were dismantled: Jülich and Berg were awarded to Wolfgang William, while the John Sigismund gained Cleves, Mark, and Ravensberg.

The background of the Dutch Revolt is also necessary to understanding the events leading up to the Thirty Years' War. It was widely known that the Twelve Years' Truce was set to expire in 1621, and throughout Europe it was recognized that at that time, Spain would attempt to reconquer the Dutch Republic. At that time, forces under Ambrogio Spinola, 1st Marquis of the Balbases, the Genoese commander of the Spanish army, would be able to pass through friendly territories to reach the Dutch Republic; the only hostile state that stood in his way was the Electorate of the Palatinate. (Spinola's preferred route would take him through the Republic of Genoa, the Duchy of Milan, through the Val Telline, around hostile Switzerland bypassing along the north shore of Lake Constance, then through Alsace, the Archbishopric of Strasbourg, then through the Electorate of the Palatinate, and then finally through the Archbishopric of Trier, Jülich and Berg and on to the Dutch Republic). The Palatinate thus assumed a strategic importance in European affairs out of all proportion to its size. This explains why the Protestant James I of England arranged for the marriage of his daughter Elizabeth Stuart to Frederick V, Elector Palatine in 1612, in spite of the social convention that a princess would only marry another royal.

By 1617, it was apparent that Matthias, Holy Roman Emperor and King of Bohemia, would die without an heir, with his lands going to his nearest male relative, his cousin Archduke Ferdinand II of Austria, heir-apparent and Crown Prince of Bohemia. With the Oñate treaty, Philip III of Spain agreed to this succession.

Ferdinand, having been educated by the Jesuits, was a staunch Catholic who wanted to impose religious uniformity on his lands. This made him highly unpopular in Protestant (primarily Hussite) Bohemia. The population's sentiments notwithstanding, the added insult of the nobility's rejection of Ferdinand, who had been elected Bohemian Crown Prince in 1617, triggered the Thirty Years' War in 1618, when his representatives were thrown out of a window and seriously injured. The so-called Defenestration of Prague provoked open revolt in Bohemia, which had powerful foreign allies. Ferdinand was upset by this calculated insult, but his intolerant policies in his own lands had left him in a weak position. The Habsburg cause in the next few years would seem to suffer unrecoverable reverses. The Protestant cause seemed to wax toward a quick overall victory.

The war can be divided into four major phases: The Bohemian Revolt, the Danish intervention, the Swedish intervention and the French intervention.