 Complete the following phrase:  From December 17, 1944, Lieutet General Shizuo Yokoyama and his Shimbu Group, an independent detachment, were made wholly responsible for the defense of southern Luzon, from Manila southwards. The Shimbu Group was officially re-designated the Japanese 41st Army on March 6, 1945. Yokoyama commanded Japanese forces defending Manila against the U.S. Sixth and Eighth Armies. Following the Battle of Manila, Yokohama withdraw his surviving forces into the mountains of southern Luzon for a protracted 