Opposition to Huerta’s smashed and tyrannical standard developed in the north, and an uncomfortable alliance was shaped between Pancho Villa, Álvaro Obregón, and Venustiano Carranza, whose Plan de Guadalupe required Huerta's resignation. In the spring and summer of 1914, the renegade powers united in Mexico City, compelling Huerta into banish. Carranza announced himself president on August 20, over Villa's complaints. A condition of political agitation and bloodshed followed until Villa, Obregón, and Zapata held a show, choosing Eulalio Gutiérrez interim president. Villa retained the support of Zapata and backed Gutiérrez. Obregón, however, re-allied himself with Carranza and routed Villa in a bloody battle in April 1915 at Celaya. From that point, both Zapata and Villa lost ground, and Villa, accusing his annihilation on U.S. President Woodrow Wilson's help of Carranza, propelled a feud against Americans in Mexico and in U.S. border towns. He executed around 17 U.S. residents at Santa Isabel in January 1916, and his assault on Columbus, New Mexico, after two months, which killed exactly 17 Americans, provoked President Woodrow Wilson to arrange Gen. John J. Pershing into the Mexican slopes in futile pursuit.