In December 1941, Iida took command of the newly formed Fifteenth Army, consisting of the 33rd and 55th Infantry Divisions, charged with occupying Thailand. Beginning on 8 December, his superior forces easily overcame light Thai resistance. The Thai government then accepted occupation and signed a mutual defense pact with Japan.
On 20 January 1942, Iida's divisions crossed into Burma. Iida had only 35,000 men and limited supplies. The terrain sharply circumscribed Japanese operations, forcing the troops to abandon most of their heavy weapons and vehicles and utilize animals to carry their provisions. Although Japanese air attacks on Rangoon failed to close that port, Iida quickly outmaneuvered British forces. The Japanese force-marched along jungle trails, often outdistancing the motorized British. On 8 March, his men took Rangoon, and Iida immediately used that port to receive reinforcements and supplies. The fall of Rangoon also cut the Burma Road and isolated China from Western aid. By May, British and Chinese forces in Burma had been driven back to India and China, respectively. The Japanese had inflicted some 30,000 casualties, with their own ground force losses numbering only 7,000.
In April 1943, Iida was assigned to the General Defense Command. He retired in December 1944 but was recalled to command the Thirtieth Army in Manchuria in July 1945. He had barely taken up his post before it was overrun by the Red Army in August. Iida was taken prisoner and only released in 1950. He died in Tokyo on 23 January 1975. Tim J. Watts
Carew, Tim. The Longest Retreat: The Burma Campaign, 1942. London: Hamilton, 1969.; Grant, Ian L., and Kazno Tamayama. Burma 1942: The Japanese Invasion. Chicester, UK: Zampi Press, 1999.; Lunt, James D. A Hell of a Licking: The Retreat from Burma, 1941–2. London: Collins, 1986.
Tim J. Watts