The Thirty Years' War was a series of wars between various Protestant and Catholic states in the fragmented Holy Roman Empire between 1618 and 1648.
The Bohemian Revolt (1618–1620) was an uprising of the Bohemian estates against the rule of the Habsburg dynasty, in particular Emperor Ferdinand II, which triggered the Thirty Years' War.
After the Bohemian Revolt was suppressed by Ferdinand II, the Danish King Christian IV, fearing that recent Catholic successes threatened his sovereignty as a Protestant nation, led troops against Ferdinand.
The Swedish Intervention in the Thirty Years' War was a major turning point of the war, where King Gustav II Adolf of Sweden ordered a full-scale invasion of the Catholic states.
No longer able to tolerate the encirclement of two major Habsburg powers on its borders, Catholic France entered the war on the side of the Protestants to counter the Habsburgs and bring the Thirty Years' War to an end.
The Peace of Westphalia was a series of peace treaties signed between May and October 1648 in the Westphalian cities of Osnabrück and Münster that ended the Thirty Years' War.