Prince Aimone Roberto Margherita Maria Giuseppe Torino (1900-1948), 4th Duke of Aosta, was born on 9 March 1900 in Turin. His parents were Prince Emanuele Filiberto, 2nd Duke of Aosta (son of Amadeus I of Spain and Princess Maria Vittoria) and Princess Hélène (daughter of Prince Philippe of Orléans and the Infanta Maria Isabel of Spain). His great grandfather was King Victor Emmanuel II of Italy, making him a member of the House of Savoy.

On 1 July 1939 Prince Aimone married Princess Irene, the daughter of King Constantine I of Greece and Princess Sophie of Prussia, in Florence. They had a son, Prince Amadeo, 5th Duke of Aosta, on 27 September 1943.

On 18 May 1941, taking the name Tomislav II, he was proclaimed King of the Independent State of Croatia, a German/Italian puppet state covering most of Croatia and Bosnia and Herzegovina. He never had any power or even set foot on the territory of the state, and subsequently abandoned the crown on 12 October 1943, after the Italian withdrawal from the war.

Prince Aimone became 4th Duke of Aosta on 3 March 1942, following the death of his elder brother Prince Amadeo, 3rd Duke of Aosta, in a British Prisoner of War camp in Nairobi. He himself died on 29 January 1948 in Buenos Aires.