Many Mexican Irish communities existed in Mexican Texas until the revolution. Many Irish then sided with Catholic Mexico against Protestant pro-US elements. The Batallón de San Patricio, a battalion of U.S. troops who deserted and fought alongside the Mexican Army against the United States in the Mexican–American War (1846–48). In some cases, Irish immigrants or Americans left from California (the Irish Confederate army of Fort Yuma, Arizona during the U.S. Civil War (1861–65). Álvaro Obregón (O'Brien) was president of Mexico during 1920-24 and Ciudad Obregón and its airport are named in his honor. Actor Anthony Quinn is another famous Mexican of Irish descent. There are also monuments in Mexico City paying tribute to those Irish who fought for Mexico in the 19th century.