The The 41st Infantry Division, composed of National Guard units from Oregon, Washington, Montana and Idaho, was ordered into federal service 16 September 1940. Originally assigned to Fort Lewis, Washington, it trained there until ordered overseas in early 1942. It was one of the first divisions to go overseas. Sailing from San Francisco, California in March 1942, it arrived in Australia in April. Training took place 60 miles north of Melbourne and after July in the tropical Rockhampton, Queensland.
The first unit to be ordered north, the 163rd Infantry Regiment arrived in New Guinea at Port Mores on 26 December 1942. The regiment was attached to the Australian 7th Division, helping to destroy the Japanese Forces along the Sananada Trail then moving into the Bunz-Gona area to close the Papuan Campaign. It was there that the 41st Division became known as the "Jungleers." By the early part of February 1943, the Division was in New Guinea to stay for a long time.
The New Guinea Campaign took the Division through Salamaua, Aitape, Hollandia, Nassua Bay, Wadke-Arare-Toem to the Biak. In late 1944, the Philippine Islands were attacked. In February 1945, the 41st Division, now part of the 6th Army, invaded Palawan. The Division was active in the southern Philippines Campaign with participation in the battles of Basilan, Jolo and Mindinao. In September, the Division left Zamboango to take up occupation duties in Japan. In October, they moved into southern Honshu, as the occupational force. The 41st Division was deactivated in Japan on 31 December 1945.