The leaders of Italian unification faced significant obstacles, as the Italian states were divided and Austria dominated much of the region, making unification seem impossible. However, Piedmont-Sardinia was able to gain allies by joining the Crimean War, and then Napoleon III agreed to aid their fight against Austria if certain territories were surrendered. This allowed Piedmont-Sardinia, with French support, to defeat Austria and gradually unite the other Italian states through military campaigns and uprisings led by Giuseppe Garibaldi.