When the First Philippine Republic was constituted on January 22, 1899 in Malolos, that municipality became the seat of government of the Philippine Republic, and was serving as such when hostilities erupted between U.S. and Filipino forces in the Second Battle of Manila on February 4. On February 4, 1899, armed conflict erupted in Manila between Philippine Republic forces and American forces occupying the city subsequent to the conclusion of the Spanish–American War. That day President Aguinaldo issued a proclamation ordering and commanding that "peace and friendly relations with the Americans be broken and that the latter be treated as enemies, within the limits prescribed by the laws of war." The fighting quickly escalated into the Second Battle of Manila, with Philippine Republic forces being driven out of the city.