I. Onset 1607-18

I. The Onset of the Thirty Years War, 1607-1618.

Dynastic ambitions, constitutional conflict, and religious fervor helped cause the Thirty Years War

Hapsburg territory 1618

The sheer extent of Hapsburg power made France and the United Provinces (Dutch Republic) fear for their independence.

The Holy Roman Emperors' attempts to assert control over the autonomous princes and cities of Germany and Central Europe produced an uneasy reaction.

The Peace of Augsburg (1555) had allowed each prince to choose whether his state should be Catholic or Protestant (Lutheran) - cuius regio eius religio. This settlement had produced temporary peace, but it led to increasing problems by the seventeenth century, especially as Calvinism (not permitted under the Peace of Augsburg) had spread, and such important figures as the Electors Palatine and Brandenburg adopted it.
[See Map]

The Roman Catholics interpreted the "ecclesiastical reservation" clause in a way that prevented the alienation of any Catholic land.

Many of the Hapsburgs' Protestant subjects were concerned by the progress of the Counter-Reformation - spearheaded by the Jesuits - and its "re-catholicization" of Austria, Styria, and Bohemia.

Germany too was destabilized by religious change: - As Lutheranism lost members to both Catholicism and Calvinism, people were forced to move in order to avoid popular violence and official harassment.

Maximilian of Bavaria
(1573-1651)

	In Imperial cities, both religions were supposed to be tolerated, but in practice the majority oppressed the minority in various ways. In Donauwörth in 1606-07, the wealthy and powerful Maximilian of Bavaria (1573-1651) invaded in the Emperor's name, after Protestants there had violently dispersed a Catholic procession. Maximilian proceeded to take personal control, and suppress all Protestant worship.
	Protestant princes protested by boycotting the Imperial Diet and forming a Protestant Union (1608) to defend their interests.
	Maximilian responded by establishing a Catholic League (1609).

In 1610, war almost broke out between the two armed groups over a disputed succession in the provinces of Cleves and Jülich. Only the assassination of Henry IV of France (an important supporter of the Protestant princes) averted war.

The Cleves-Jülich succession crisis

Duke John William of Cleves died - childless and insane - in March 1609.
Two Protestant princes, Philip Louis, Count Palatine of Neuburg (married to the Duke’s sister Anna) and John Sigismund Hohenzollern, Elector of Brandenburg, (son-in-law of another sister of the Duke) obtained Henry IV's support and occupied the Duke's lands.
Supporting the rival claim of the Elector of Saxony, the Hapsburgs sent Spanish and Imperial troops into Cleves and Jülich. The neighboring Dutch seized the fortress of Jülich.
The Count Palatine of Neuburg and the Hohenzollerns of Brandenburg later fell out with one another, and the dispute was only finally settled (by dividing the territories) in 1666.

The Protestant Union of German princes sought English and Dutch help to counter Hapsburg power. Yet German Protestants - especially the cities - were also fearful of being dragged into any renewal of the perennial conflict between Spain and the United Provinces.
Christian I of Anhalt (1568-1630), a firm Calvinist, did his best to strengthen the resolve of the Protestant Union, but with little success.