Thirty Years' War
The Thirty Years' War, fought primarily in Central Europe between 1618 and 1648, was one of the most destructive conflicts in European history. An estimated 4.5 to 8 million soldiers and civilians died from the effects of battle, famine, or disease, with parts of Germany reporting population declines of over 50%. Related conflicts include the Eighty Years' War, the War of the Mantuan Succession, the Franco-Spanish War, the Torstenson War, the Dutch–Portuguese War, and the Portuguese Restoration War.
Its causes derived from religious conflict within the Holy Roman Empire, sparked by the 16th-century Reformation. The 1555 Peace of Augsburg attempted to resolve this by dividing the Empire into Catholic and Lutheran states, but was later destabilised by the expansion of Protestantism beyond these boundaries. Combined with disagreements over the limits of imperial authority, religion was thus an important factor in starting the war. However, its scope and extent was largely the consequence of external drivers such as the French–Habsburg rivalry and the Dutch Revolt.
The war began in 1618, when the Catholic Emperor Ferdinand II was replaced as king of Bohemia by the Protestant Frederick V of the Palatinate. Although Ferdinand quickly regained control of Bohemia, Frederick's participation expanded fighting into the Palatinate, whose strategic importance drew in the Dutch Republic and Spain, then engaged in the Eighty Years' War. In addition, the acquisition of territories within the Empire by rulers like Christian IV of Denmark and Gustavus Adolphus of Sweden gave them and other foreign powers an ongoing motive to intervene. Combined with fears that the Protestant religion in general was threatened, these factors turned an internal dynastic dispute into a European conflict.
The period from 1618 to 1635 was primarily a civil war within the Holy Roman Empire, which largely ended with the Peace of Prague. However, France's entry into the war in alliance with Sweden turned the empire into one theatre of a wider struggle with their Habsburg rivals, Emperor Ferdinand III and Spain. Fighting ended with the 1648 Peace of Westphalia, whose terms included greater autonomy for states like Bavaria and Saxony, Swedish territorial gains in northern Germany, as well as acceptance of Dutch independence by Spain. The conflict shifted the balance of power in favour of France and its subsequent expansion under Louis XIV.
Structural origins
The 16th century Reformation caused open warfare between Protestants and Catholics within the Holy Roman Empire, which ended with the 1552 Peace of Passau. The Peace of Augsburg in 1555 tried to prevent a recurrence by fixing boundaries between the two faiths, using the principle of cuius regio, eius religio. States were designated as either Lutheran, then the most usual form of Protestantism, or Catholic, based on the religion of their ruler. Other provisions protected substantial religious minorities in cities like Donauwörth, and confirmed Lutheran ownership of property taken from the Catholic Church since 1552.However, the settlement was undermined by the expansion of Protestantism into Catholic areas post-1555, particularly Calvinism, a Protestant doctrine viewed with hostility by both Lutherans and Catholics. Augsburg also gave individual rulers significantly greater autonomy, allowing larger states to pursue their own objectives, which often clashed with those of central authority or external powers. Conflict sometimes superseded religion, with the Protestant states of Saxony and Brandenburg competing with Denmark–Norway and Sweden over the lucrative Baltic trade.
Reconciling these differences was hampered by fragmented political institutions, which included 300 imperial estates distributed across Germany, the Low Countries, northern Italy, and present-day France. These ranged in size and importance from the seven Prince-electors who voted for the Holy Roman Emperor, down to Prince-bishoprics and imperial cities like Hamburg. Each also belonged to a separate regional grouping known as an Imperial Circle, which was chiefly concerned with defence, and operated independently. Above all of these was the Imperial Diet, which assembled infrequently, and focused on discussion, rather than legislation.
Since 1440, the position of emperor had been held by the House of Habsburg, the largest single landowner within the Holy Roman Empire. They directly ruled over eight million subjects and territories that included Austria, Bohemia and Hungary. The Habsburgs also controlled the Spanish Empire until 1556, when Charles V divided his possessions between different branches of the family. This bond was reinforced by frequent inter-marriage, while Spain retained territories within the Holy Roman Empire such as the Spanish Netherlands, Milan and Franche-Comté. However, although the two often collaborated, there was no such thing as a joint "Habsburg" policy.
File:Vroom Hendrick Cornelisz Dutch Ships Ramming Spanish Galleys off the Flemish Coast in October 1602.jpg|thumb|Dutch ships ramming Spanish galleys in the Battle of the Narrow Seas during the Eighty Years' War, October 1602
This is because the two entities were very different. Spain was a global maritime superpower, stretching from Europe to the Philippines and the Americas, while Austria was a land-based power, focused on Germany and securing its eastern border against the Ottoman Empire. Another key difference was the disparity in relative financial strength, with the Spanish Habsburgs providing large subsidies to their Austrian counterparts. The loss of these post 1640, as Spain itself struggled with the costs of a long running global war, substantially weakened the imperial position.
Prior to the Reformation, shared religion partially compensated for weak imperial institutions. After 1556, rising religious and political tensions allowed states like Lutheran Saxony and Catholic Bavaria to expand their own power, while further weakening imperial authority. This internal political struggle was exacerbated by external powers with their own strategic objectives, such as Spain, the Dutch Republic, or France, confronted by Habsburg lands on its borders to the north, south, and along the Pyrenees. Since a number of foreign rulers were also imperial princes, divisions within the empire drew in players like Christian IV of Denmark, who joined the war in 1625 as Duke of Holstein-Gottorp.
History
Background: 1556 to 1618
Disputes occasionally resulted in full-scale conflict like the 1583 to 1588 Cologne War, triggered when its ruler converted to Calvinism. More common were events such as the 1606 Battle of the Flags in Donauwörth, when riots broke out after the Lutheran majority blocked a Catholic religious procession. Emperor Rudolf approved intervention by the Catholic Maximilian of Bavaria. In return, he was allowed to annex the town, and, as agreed at Augsburg, the official religion changed from Lutheran to Catholic.When the Imperial Diet opened in February 1608, both Lutherans and Calvinists sought re-confirmation of the Augsburg settlement. In return, the Habsburg heir Archduke Ferdinand required the immediate restoration of any property taken from the Catholic Church since 1555, as opposed to the previous practice whereby each case was assessed separately. By threatening all Protestants, his demand paralysed the diet and removed the perception of imperial neutrality.
The loss of faith in central authority meant towns and rulers began strengthening their fortifications and armies, with foreign travellers often commenting on the militarisation of Germany in this period. When Frederick IV, Elector Palatine formed the Protestant Union in 1608, Maximilian responded by setting up the Catholic League in July 1609. Both were largely vehicles for their leaders' dynastic ambitions, but when combined with the 1609 to 1614 War of the Jülich Succession, the result was to increase tensions throughout the empire. Some historians who see the war as primarily a European conflict argue that Jülich marks its beginning, with Spain and Austria backing the Catholic candidate, France and the Dutch Republic the Protestant.
File:CaminoEspañol.svg|thumb|right|upright=0.8|The Spanish Road
Purple: Spanish dependencies
Green: Ruled by Austria
Orange: Ruled by Spain
External powers became involved in what was an internal German dispute because of the imminent expiry of the 1609 Twelve Years' Truce, which suspended the Eighty Years' War between Spain and the Dutch Republic. Before restarting hostilities, Ambrosio Spinola, commander in the Spanish Netherlands, needed to secure the Spanish Road, an overland route connecting Habsburg possessions in Italy to Flanders. This allowed him to move troops and supplies by road, rather than sea where the Dutch navy was dominant; by 1618, the only part not controlled by Spain ran through the Electoral Palatinate.
Since Emperor Matthias had no surviving children, in July 1617 Philip III of Spain agreed to support Ferdinand II's election as king of Bohemia and Hungary. In return, Ferdinand made concessions to Spain in northern Italy and Alsace, and agreed to support their offensive against the Dutch. Doing so required his election as emperor, which was not guaranteed; Maximilian of Bavaria, who opposed the increase of Spanish influence in an area he considered his own, tried to create a coalition to support his candidacy.
Another option was Frederick V, Elector Palatine, a Calvinist who in 1613 married Elizabeth of Bohemia, daughter of James I of England. When Ferdinand was elected king of Bohemia in 1617, he also gained control of its electoral vote, but his conservative Catholicism made him unpopular with the mostly Protestant Bohemian nobility, who were also concerned about the erosion of their rights. Since the seven electors previously consisted of three Protestants and four Catholics, replacing Ferdinand with Frederick would alter the religious balance, making possible the election of a Protestant emperor and the end of Habsburg predominance. These factors combined to bring about the Bohemian Revolt in May 1618.