The Habsburg dynasty held the Holy Roman imperial throne during the Thirty Years’ War. From 1618 to 1648, the emperors Ferdinand II and Ferdinand III—both members of the House of Habsburg—ruled the Empire.
The Habsburgs had held the imperial office continuously since 1438, apart from the brief reign of Charles VII of Bavaria from 1742 to 1745. Their power rested on hereditary lands including Austria, Bohemia, and Hungary, as well as extensive family connections across Europe. Emperor Ferdinand II’s attempt to strengthen Catholic authority and imperial control helped trigger the Bohemian revolt that began the war.
The conflict was not simply a war between the Habsburgs and every Protestant state. It involved shifting alliances, internal imperial politics, Denmark, Sweden, Spain, and eventually France. France entered the war despite being Catholic because it opposed Habsburg encirclement and Spanish influence.
The Wittelsbach dynasty briefly supplied a rival imperial candidate, Frederick V, while the Hohenzollerns and Bourbons did not hold the imperial throne during this war.