The king died in 1740 and was succeeded by his son, Frederick II, whose accomplishments led to his reputation as "Frederick the Great". As crown prince, Frederick had focused, primarily, on philosophy and the arts. He was an accomplished flute player. In 1740, Prussian troops crossed over the undefended border of Silesia and occupied Schweidnitz. Silesia was the richest province of Habsburg Austria. It signalled the beginning of three Silesian Wars (1740–1763). The First Silesian War (1740–1742) and the Second Silesian War (1744–1745) have, historically, been grouped together with the general European war called the War of Austrian Succession (1740–1748). Holy Roman Emperor Charles VI had died on 20 October 1740. He was succeeded to the throne by his daughter, Maria Theresa.