The 'Battle of Batan Island' was the first step in the Japanese 'M' (ii) invasion of the Philippines (8 December 1941).
The purpose was to obtain control of local air strips for use as forward bases by fighter aircraft for operations farther to the south in the main part of the Philippine islands group. The attack on Batan Island was the first of several advance landings, and thus preceded those at Aparri, Vigan, Legaspi, Davao and Jolo island.
The Japanese had been formally planning an attack on the US Pacific Fleet at its main base at Pearl Harbor in the Hawaiian islands group since a time early in 1941, but the idea had been informally speculated for many years. After the 1931 Japanese invasion of Manchuria, beginning the 2nd Sino-Japanese War, Japan spent considerable effort trying to isolate China and to obtain sufficient natural resources to attain victory in China. The 1940 Japanese invasion of Vichy French Indo-China was another such an effort to control supplies as well as secure forward basing facilities for the planned 'E' (i) invasion of Malaya. In response, the USA halted shipments of aircraft, parts, machine tools, and aviation fuel to Japan. In July 1941, the US ended oil exports to Japan, leaving the Japanese with the option either of withdrawing from China or of securing new sources of raw materials in the resource-rich but European-controlled colonies of South-East Asia, such as Malaya and the Netherlands East Indies.
Early in 1941, President Franklin D. Roosevelt ordered a military build-up in the Philippine islands group in the hope of discouraging further Japanese aggression in the Far East. Because the Japanese high command was certain that any attack on the British colonies in South-East Asia would bring the USA intro World War II, and therefore planned the devastating first strike on Pearl Harbor in 'Ai' and the Philippine islands group in 'M' (ii).
As noted above, the island of Batan was the first part of the Japanese invasion of the Philippine islands group, and occurred simultaneously with the attack on Pearl Harbor. Its main purpose was set up an air base for future operations against the US and Philippine forces on Luzon, the largest and northernmost island of the Philippines.
The landing on Batan was launched by the Batan Attack Force from the port of Takao on the south-western coast of Japanese-occupied Formosa on 8 December 1941. The Batan island invasion force, under the overall command of Vice Admiral Sueto Hirose, comprised a 490-man naval combat unit and an indeterminate number of air corps troops, carried in the transport vessels Teiun Maru and Kumagawa Maru escorted by the destroyer Yamagumo, the torpedo boats Chidori, Manazuru, Tomozuru and Hatsukari, the minesweepers W-13 amd W-14, the patrol boats PB-1 and PB-2, nine converted submarine-chasers (Shonan Maru No. 17, Takunan Maru No. 5, Fukuei Maru No. 15, Kyo Maru No. 2, Kyo Maru No. 11, Koeri Maru, Shonan Maru No. 1, Shonan Maru No. 2 and Nagara Maru), the minelayers Kamome and Tsubame, and the converted gunboats Aso Maru, Koso Maru and Nampo Maru. The combat troops quickly secured the existing small airfield outside Basco without meeting any resistance, and the air corps troops began work on the following day to enlarge the airfield and its facilities to make it suitable for the operation of fighters and reconnaissance aircraft. On this same day, the first aircraft of the Imperial Japanese army air force’s 24th and 50th Fighter Regiments landed at Basco.
Over the next few days, however, the success of the Japanese bombing of Clark Field rendered the base at Basco redundant, and work was discontinued. On 10 December, the Batan Attack Force was withdrawn to land on Camiguin island in the Babuyan Islands group slightly farther to the south. The landing again proceeded without incident, and possession of the small airstrip on Camiguin gave the Japanese a forward air base only 35 miles (56 km) from Aparri. The Japanese also occupied nearby Calayan island.
In retrospect, the advance landings in northern Luzon, including those on Batan and Camiguin islands, accomplished little of strategic or tactical value. The airfields seized were small, and with the rapid advance of the Japanese into central Luzon, were soon unnecessary for further operations.