Charles was born in Florence, Tuscany. His father, then Grand Duke of Tuscany, generously permitted Charles's childless aunt Archduchess Maria Christina of Austria and her husband Albert of Saxe-Teschen to adopt and raise the boy in Vienna. Charles spent his youth in Tuscany, at Vienna and in the Austrian Netherlands, where he began his career of military service in the wars of the French Revolution. He commanded a brigade at the Battle of Jemappes (1792), and in the campaign of 1793 distinguished himself at the Action of Aldenhoven and the Battle of Neerwinden. In this year he became Governor of the Habsburg Netherlands, an office he lost with the occupation of the Low Countries by the French revolutionaries in 1794. The year he became Governor he also received the army rank of Lieutenant Field Marshal. Shortly thereafter another promotion saw him made "Feldzeugmeister" (equivalent of Lieutenant General). In the remainder of the war in the Low Countries he held high commands, and was present at the Battle of Fleurus (1794).