Answer
Prince Amedeo, Duke of Aosta, was the head of a cadet branch of the House of Savoy who disputed the succession to the Italian throne with Vittorio Emanuele after the abdication of King Umberto I. Amedeo was seen by many as the legitimate heir due to his closer relation to the main branch of the family, while Vittorio Emanuele was the son of Umberto I's cousin.