Complex sentence: After the war his family were declared state enemies by Josip Broz Tito's communist regime; however, George was allowed to retire in Belgrade as the only member of Royal family in the country.
Split into simpler sentences: After the war the royal Karađorđević family was declared enemy-of-the-state by Josip Broz Tito's communist regime. However, George was allowed to retire in Belgrade as the only member of the Royal family in the country.