Complex sentence: Iwabuchi had 12,500 men under his command, designated the Manila Naval Defence Force, augmented by 4,500 army personnel under Col. Katsuzo Noguchi and Capt. Saburo Abe.
Split into simpler sentences: Iwabuchi had 12,500 men under his command, designated the Manila Naval defence Force. Iwabuchi was joined by 4500 army personnel under the command of Col. Katsuzo Noguchi and Capt. Saburo Abe.