‘The early modern empire (1): from Maximilian I to the Thirty Years War’ outlines the period from 1493 to 1648. Maximilian I’s reign (1493–1519) transformed the empire. It remained a feudal society, in which the princes owed allegiance to the emperor, but it now gained more elements of a written constitution. Subsequently, the empire acquired a more extensive body of constitutional law than any other early modern European monarchy. The reigns of Charles V, Ferdinand I, and Maximilian II, and key events including Martin Luther’s Reformation movement, the Peace of Augsburg in 1555, and the Thirty Years War (1618–48) that started with a Bohemian rebellion against Habsburg rule, are all described.