The Thirty Years' War

Thirty Years' War (1618-1648)

Began as a religious conflict between Protestants and Catholics within the Holy Roman Empire (HRE).
Holy Roman Emperor Ferdinand II attempted to enforce religious uniformity, violating the Peace of Augsburg.
Protestant princes united against the emperor, aided by England.
Habsburg Spain, Austria, Italy, and Poland supported the emperor.
Sweden's entry under Gustavus Adolphus prolonged the conflict, driven by territorial expansion.
France (Catholic) joined the Protestants to weaken Habsburg Spain and the HRE, shifting the war's focus to political gain.

Negotiated in Westphalia, Germany, marking the Catholic surrender after Sweden and France proved too strong.
Sweden and France gained land from Catholic regions of the HRE and Spain.
The Netherlands gained independence from Spain.
German princes could choose any religion, free from Holy Roman Emperor's control.

Last major religious war in Europe; conflicts shifted to balance of power.
Nations aimed to prevent any single state from dominating Europe.
Peace talks included all parties involved in the conflict.
Centralized states (France, Sweden) with national taxes and armies proved superior to non-centralized states.
Spain and the Holy Roman Empire's power diminished, focusing on the Ottoman threat.
Over 1/3 of the German population in the HRE died during the war.