 Eichelberger had misgivings about the projected timetable for the operation, but nonetheless, his Eighth Army staffers came up with a more effective plan.On the same day Eichelberger's forces were ordered to invade Mindanao, remnants of Maj. Gen. Jens A. Doe's 41st Infantry Division carried out Operation VICTOR IV, the seizure of Zamboanga, which was concurrent with the recapture of Palawan, dubbed Operation VICTOR III.A sizable force, numbering about 9,000 men of the 54th Japanese Independent Mixed Brigade (IMB), had established strong defensive positions around Zamboanga City at the southern tip of the peninsula.