It is difficult to say who “the leader” of the Italian nationalist movement was. There are three men who are famous today as leaders of the Italian nationalist movement. Two of them were mostly military leaders while the third was a political leader who did the most to actually achieve Italian unification. The two military leaders were Giuseppe Mazzini and Giuseppe Garibaldi. These two began fighting for Italian unification in the 1830s. They were never quite able to achieve it on their own, but they were deeply involved in the nationalist movement. The third man was Count Camillo Cavour. He was the prime minister of Piedmont, one of the Italian states. Cavour used the power of his office to work to unify Italy.
Italy gained its independence through political maneuvering and military action. At that time, Austria controlled much of what is now Italy. France and Austria were rivals for power in Europe. Therefore, Cavour used diplomacy to make an alliance with France. This caused France to help Piedmont fight the Austrians. It was mainly through this war that Italy became independent and unified.
German unification was achieved in a way that was both similar to and different from Italian unification. The two unifications were similar in that both involved military action. However, the German unification did not involve ejecting foreign powers from Germany. Instead, it involved Prussia fighting Austria (both were German states) for dominance. Prussia also fought other countries like Denmark and France, but it did not do this to eject them from German territory. Instead, it did so to gain power. When it gained power, more of the small German states became interested in unifying with Prussia.