Charles V

Charles V (1500-1558) ruled an accumulation of territories larger than that of any European monarch since Charlemagne, assembled almost entirely by inheritance. Born at Ghent, he was the eldest son of Philip the Handsome and Juana of Castile, and thus the grandson of Maximilian I and Mary of Burgundy on one side and of Ferdinand of Aragon and Isabella of Castile on the other. His father's death in 1506 made him duke of the Burgundian Netherlands, where he was raised under the guardianship of his aunt Margaret of Austria; the death of Ferdinand of Aragon in 1516 brought him Castile and Aragon, with Naples, Sicily, Sardinia, and the expanding American possessions, ruling nominally with his confined mother. When Maximilian died in 1519, Charles inherited the Austrian lands and was elected Holy Roman Emperor over the rival candidacy of Francis I of France.

The scale of the inheritance dictated its problems. By the treaties of Worms and Brussels (1521-1522) Charles transferred the Austrian territories to his younger brother Ferdinand, who became his lieutenant in the Empire and, through his Jagiellon marriage, king of Bohemia and Hungary from 1526 — the origin of the Austrian branch of the house. Charles himself fought four wars against Francis I over Italy and Burgundy, capturing the French king at Pavia in 1525, and confronted Ottoman expansion under Suleiman, whose forces besieged Ferdinand's Vienna in 1529; Charles led the capture of Tunis in 1535.

The Reformation defined his reign in Germany. He presided over the Diet of Worms in 1521, where Luther refused to recant, and after decades of inconclusive negotiation defeated the Protestant Schmalkaldic League at Mühlberg in 1547. The victory proved unusable: a princely revolt in 1552 forced him to accept the religious settlement concluded by Ferdinand at Augsburg in 1555, which recognized Lutheranism within the Empire.

In 1526 Charles married Isabella of Portugal, a union that strengthened the Iberian orientation of his line; their son Philip was raised as a Spanish prince. Exhausted and afflicted by gout, Charles abdicated in stages in 1555-1556, leaving Spain, the Netherlands, and Italy to Philip II and the imperial office to Ferdinand I, formalizing the division between Spanish and Austrian Habsburgs. He retired to a house adjoining the monastery of Yuste in Extremadura, where he died on 21 September 1558.