Charles V (Spanish: Carlos; German: Karl; Italian: Carlo; Dutch: Karel; Latin: Carolus; 24 February 1500 – 21 September 1558) was ruler of both the Holy Roman Empire from 1519 and the Spanish Empire (as Charles I of Spain) from 1516, as well as of the lands of the former Duchy of Burgundy from 1506. He stepped down from these and other positions by a series of abdications between 1554 and 1556. Through inheritance, he brought together under his rule extensive territories in western, central, and southern Europe, and the Spanish viceroyalties in the Americas and Asia. As a result, his domains spanned nearly 4 million square kilometres (1.5 million square miles), and were the first to be described as "the empire on which the sun never sets".
Charles was the heir of three of Europe's leading dynasties: Valois of Burgundy, Habsburg of Austria, and Trastámara of Spain. As heir of the House of Burgundy, he inherited areas in the Netherlands and around the eastern border of France. As a Habsburg, he inherited Austria and other lands in central Europe, and was also elected to succeed his grandfather, Maximilian I, as Holy Roman Emperor. As a maternal grandson of the Catholic Monarchs of Spain, from the Spanish House of Trastámara he inherited the Crown of Castile, which was developing a nascent empire in the Americas and Asia, and the Crown of Aragon, which included a Mediterranean empire extending to southern Italy. Charles was the first king to rule Castile and Aragon simultaneously in his own right (as a unified Spain), and as a result he is often referred to as the first king of Spain.[a] The personal union under Charles of the Holy Roman Empire with the Spanish Empire was the closest Europe would come to a universal monarchy since the time of Charlemagne in the 9th century.
Because of widespread fears that his vast inheritance would lead to the realization of a universal monarchy and that he was trying to create a European hegemony, Charles was the object of hostility from many enemies. His reign was dominated by war, particularly by three major simultaneous conflicts: the Habsburg-Valois Wars with France, the struggle to halt the Turkish advance into Europe, and the conflict with the German princes resulting from the Protestant Reformation. The French wars, mainly fought in Italy, lasted for most of his reign. Enormously expensive, they led to the development of the first modern professional army in Europe, the Tercios.
The struggle with the Ottoman Empire was fought in Hungary and the Mediterranean. The Turkish advance was halted at the Siege of Vienna in 1529, and a lengthy war of attrition, conducted on Charles' behalf by his younger brother Ferdinand (King of Hungary and archduke of Austria), continued for the rest of Charles's reign. In the Mediterranean, although there were some successes, he was unable to prevent the Ottomans' increasing naval dominance and the piratical activity of the Barbary corsairs. Charles opposed the Reformation and in Germany he was in conflict with Protestant nobles who were motivated by both religious and political opposition to him. He could not prevent the spread of Protestantism and was ultimately forced to concede the Peace of Augsburg of 1555, which divided Germany along denominational lines.
While Charles did not typically concern himself with rebellions, he was quick to put down three particularly dangerous rebellions, in the vital territories of Castile, the Frisian lands, and later in his reign in the city of Ghent. Once the rebellions were quelled the essential Castilian and Burgundian territories remained mostly loyal to Charles throughout his rule.
Charles's Spanish dominions were the chief source of his power and wealth, and they became increasingly important as his reign progressed. In the Americas, Charles sanctioned the conquest by Castillian conquistadores of the Aztec and Inca empires. Castillian control was extended across much of South and Central America. The resulting vast expansion of territory and the flows of South American silver to Castile had profound long term effects on Spain.
Charles was only 56 when he abdicated, but after 40 years of active rule he was physically exhausted and sought the peace of a monastery, where he died at the age of 58. The Holy Roman Empire passed to his younger brother Ferdinand, archduke of Austria, while the Spanish Empire, including the possessions in the Netherlands and Italy, was inherited by Charles's son Philip II of Spain. The two empires would remain allies until the 18th century (when the Spanish branch of the House of Habsburg became extinct).