 These warlords were only interested in keeping their own power and defected to the Japanese when Japanese invaders offered to let them keep their power in exchange for their collaboration.After World War II these forces once again returned to the Nationalist camp for the same reason they defected to the Japanese invaders.Obviously it was difficult for Chiang to immediately get rid of these warlords as soon as they surrendered to Chiang and rejoined the Nationalists, because such a move would alienate other factions within the Nationalist ranks, and these former warlords could still help the Nationalists gain more territories by holding on to what was under their control until Chiang completed the deployment of his own troops to take over.