The controversial leader known for uniting Italy in the 19th century was Giuseppe Garibaldi. A key figure in the Risorgimento, Garibaldi played a vital role in the unification of Italy through military campaigns and strategic alliances. His most notable achievement was the successful liberation of the Kingdom of the Two Sicilies, which he then handed over to King Victor Emmanuel II, solidifying their alliance. Garibaldi's charismatic leadership and dedication to the cause of Italian nationalism made him a national hero. His legacy lives on as a symbol of the struggle for independence and unification in Italy.