Data
Date	1618-1648.
Location	Central Europe.
Belligerents	Holy Roman Empire, Spain and the German Catholic League vs. Bohemia, the Evangelical Union, Denmark, Sweden, the Netherlands, France and Transylvania.
Outcome	Franco-Swedish victory.

The 30 Years’ War was a political-religious war that took place in Central Europe and in which the main European powers of the first half of the seventeenth century participated . This began in 1618 and ended in 1648.

It began as a religious confrontation between Protestants and Catholics in the territory of the Holy Roman Empire , however as it spread, it dragged the main European powers of the first half of the seventeenth century to the battlefield.

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In this war 2 great sides faced :

• Catholics : made up of the Holy Roman Empire, Spain and the German Catholic League. The leaders of this block were Emperor Ferdinand II of Habsburg and the Count Duke of Olivares, valid of the King of Spain, Felipe IV.
• Protestants: made up of Bohemia, Denmark, Sweden, the Netherlands, the Evangelical Union and Transylvania. In addition, they were supported by France, which even being a Catholic country, got involved in the war to fight against the Habsburg dynasty, which ruled the Holy Empire. The leaders of this bloc were the King of Bohemia Frederick I, King Christian IV of Denmark, the Swedish King Gustav Adolf II and Cardinal Richelieu, Prime Minister of the King of France, Louis XIII.

The episode that triggered the war was the “defenestration of Prague”, an event that took place on May 23, 1618 in Bohemia. The war ended in 1648, with the signing of the Peace of Westphalia .

Development of the 30 Years’ war

Historians divide the war into 5 phases:

• Bohemian phase (1618-1620) : it had the character of a civic-religious war, since it was an insurrection of the Czech Protestants of Bohemia against the Catholic emperor Ferdinand II. It began with the so-called “Defenestration of Prague,” during which Protestants threw various representatives of the emperor out of the windows of the royal palace. They then organized a provisional government which they offered to the Calvinist Frederick V of the Palatinate, who was crowned Frederick I of Bohemia. The Czechs appealed to the Evangelical Union, which brought together the Lutheran and Calvinist German states, for help.. Fernando II, requested the assistance of the German and Spanish Catholic League, with whose forces he defeated the Protestants in the Battle of the White Mountain and crushed the Bohemian rebellion.
• Palatine phase (1621-1625) : after having pacified the east of the Holy Empire, Ferdinand II turned to the west and occupied the Palatinate. The Evangelical Union was dissolved and Frederick V went into exile in the Netherlands.
• Danish phase (1625-1629) : it began when the Lutheran Christian IV, king of Denmark, attacked the Holy Empire. Ferdinand II recruited an army of mercenaries that contained the Danes and then invaded Denmark. This phase of the war ended with the signing of the Treaty of Lübeck (1629), through which Christian IV resigned to support the German Protestants.
• Swedish phase (1630-1635) : began with the invasion of the King of Sweden, the Lutheran Gustavus Adolf II, to the Holy Empire. Between 1630 and 1633, the Swedes defeated the imperial forces several times, although they had to mourn the death of their king. These victories forced Ferdinand II to sign the Peace of Prague (1635) with the Protestants. Calvinism was legalized, in exchange for the commitment of all German princes to form a common army to confront the Swedes.
• Franco-Swedish phase (1636-1648) : the Peace of Prague was repudiated by France. In this phase, during which the war became international, the balance tipped to the side of the Swedes and the French, who with their decisive victories forced Emperor Ferdinand III, successor to Ferdinand II, to negotiate peace.

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Causes and consequences of the 30 Years war

Causes

The main causes of the 30 Years’ War were the following:

• The rivalry between the two predominant cults in the Holy Roman Empire: the Catholic and the Lutheran . The Peace of Augsburg , signed in 1555 between Emperor Charles V and the German princes, had tried to put an end to these rivalries. However, in the early 17th century, religious tensions increased and led to the creation of two competing alliances: the Evangelical Union (1608), which was a coalition of Lutheran and Calvinist German states, and the German Catholic League (1609) , which grouped the Catholic princes.
• The struggle for European preponderance between France and the Habsburg dynasty, which ruled the Spanish Empire, Austria, Bohemia, Hungary, and the Holy Roman Empire.
• The will of Emperor Ferdinand II to extend the Counter-Reformation and transform the Holy Empire into a centralized and hereditary State , modifying the federal and elective character that it had until then.
• The fear of the kings of France, Denmark and Sweden, that the Holy Empire would become a great power if it was unified and centralized.

Consequences

The main consequences of the 30 Years’ War were as follows:

• France, victorious, became the main European power . Spain, for its part, was weakened by the loss of Portugal (1640) and that of the United Provinces of the Netherlands (1648), which became independent. The war between France and Spain lasted until 1659 and ended with the Peace of the Pyrenees, which enshrined French supremacy and Spanish decadence .
• The Helvetic Confederation (present-day Switzerland) separated from the Holy Empire and was recognized as an independent state .
• The Holy Empire maintained its federal political organization and its elective monarchy, just as it was before the war. In this way the Habsburg project to unify the Empire and centralize its power failed.
• The validity of the principle known as “whose region is, is religion” was confirmed. This enshrined the freedom of the German princes to choose the religion of their territories according to their conscience, but it meant the obligation of their subjects to profess that religion or to emigrate.
• The death of 4,000,000 people between civilians and military. The most affected state was the Holy Empire, which lost 30% of its inhabitants and 50% of its male population. The greatest demographic catastrophe was suffered by Brandenburg, which lost 50% of its population.