The Japanese Invasion of Aparri (Filipino: Paglusob ng mga Hapones sa Aparri) on 10 December 1941 was one in a series of advance landings made by Imperial Japanese forces as first step in their invasion of the Philippines. The purpose was to obtain control of local air strips, which could be used as forward bases by fighter aircraft for operations further south. The first invasion was at Batan Island on 8 December 1941. This was followed by Vigan, Legaspi, Davao, and Jolo Island over the next few days Disposition of forces Prior to World War II, Aparri was considered a substantial port city, with a population of 26,500. However, although located at the mouth of the Cagayan River, it is isolated from the rest of Luzon by mountain ranges to the east, west, and south. Manila and the central plains of Luzon were connected to Aparri by Route 5 through the narrow Balete Pass to the south, or by a long coastal route. The Cagayan Valley was not regarded by the Americans as a route of invasion. The area of Aparri was in theory defended by General Wainwright's North Luzon Force. However, with only a few men and a large territory to cover, Wainwright could spare only one partially trained and equipped Philippine Army division, the 11th Division, commanded by Colonel William E. Brougher, for all of northern Luzon. A reserve division, the 11th had begun to mobilize only in September and was at only two-thirds of its authorized strength of 1500 men per regiment. It also suffered from a serious shortage of equipment, including almost all of its artillery and transports. This division maintained only one battalion in the entire Cagayan Valley, with only one company actually at Aparri. On the Japanese side, General Homma had organized a detachment from the IJA 48th Division’s 2nd Infantry Regiment under Colonel Toru Tanaka. This numbered approximately 2000 men of the 2nd Battalion, half the 1st Battalion and the regimental headquarters. The invasion force was supported by a flotilla of the Imperial Japanese Navy led by Vice Admiral Kenzaburo Hara, consisting of the light cruiser , destroyers , , , , , , three minesweepers, six anti-submarine craft and six transports. The fleet deployed from Mako in the Pescadores and arrived at Aparri before dawn on 10 December. The landing operation was covered by aircraft of the IJAAF 24th and 50th Fighter