sentences:  Obregón was one of three revolutionary generals from Sonora, with Plutarco Elías Calles and Adolfo de la Huerta, who were important for the post-revolutionary history of Mexico.Their collective and then internecine struggles for power in the decade after the end of the military phase of the Mexican Revolution had a direct impact on the formation of the party in 1929.In 1920, the Sonorans staged a coup against President Venustiano Carranza, the civilian First Chief of the Constitutionalist faction that had won the Mexican Revolution.