 Complete the following phrase:  The same was true of the Mexican Revolution 19101920, which had degenerated into factional fighting among the rebels by 1915, as the more radical forces of Emiliano Zapata and Pancho Villa lost ground to the more conservative Sonoran oligarchy and its Constitutional Army. The Felicistas, the last major group of counterrevolutionaries, abandoned their armed campaign in 1920, and the internecine power struggles abated for a time after revolutionary General Álvaro Obregón had bribed or slain his former allies and rivals alike, but the following decade witnessed the assassination of Obregon and several others, abortive military coup attempts and a massive traditionalist uprising, the 