The Schmalkaldic War was the short period of violence from 1546 until 1547 between the forces of Emperor Charles V of the Holy Roman Empire, commanded by the Duke of Alba and the Duke of Saxony, and the Lutheran Schmalkaldic League within the domains of the Holy Roman Empire.

Charles V was Holy Roman Emperor and Archduke of Austria from 1519 to 1556, King of Spain from 1516 to 1556, and Lord of the Netherlands as titular Duke of Burgundy from 1506 to 1555. He was heir to and then head of the rising House of Habsburg. His dominions in Europe included the Holy Roman Empire, extending from Germany to northern Italy with rule over the Austrian hereditary lands and Burgundian Low Countries, and Spain with its possessions of the southern Italian kingdoms of Naples, Sicily and Sardinia. In the Americas, he oversaw the continuation of Spanish colonization and a short-lived German colonization. The personal union of the European and American territories he ruled was the first collection of realms labelled "the empire on which the sun never sets".