Zayas became leader of the Liberal Party (left-wing) and was elected Vice-President 1908. In the contested, 1916 presidential election in which the populist Liberal Party used violent tactics, he obtained more votes than the pro-U.S. candidate, Cornell graduate General Mario García Menocal. The Chambelona War ensued, which, after some reverses, was won by the Conservative Forces of Garcia Menocal with the covert support of the United States. Zayas surrendered in Cambute near Guanabacoa where it was said he was hiding. The United States provided military support to García Menocal from Guantánamo Naval Base, without formally invoking its right of intervention pursuant to the Platt Amendment, incorporated in the U.S.-Cuba Treaty of 1903. However, the United States only deployed forces in Oriente Province.