Although Belgium was officially neutral throughout his reign, significant numbers of Belgians volunteered to fight for right-wing causes abroad. From 1860, large numbers of Belgian Catholic volunteers went to Italy in an ultimately unsuccessful attempt to defend the independence of the Papal States against Giuseppe Garibaldi's revolutionaries. The Zouaves, as they were known, were ultimately unsuccessful and the Papal States fell in 1870. A volunteer Belgian Legion fought alongside French forces in the Mexican Adventure from 1864 on behalf of Mexican Emperor Maximilian I, whose wife was the daughter of Leopold I. The unit suffered heavy casualties at the Battle of Tacámbaro in 1865, and after heavy fighting was disbanded in December 1866.