As the international situation worsened in the 1930s, the intensity and urgency of training in the 41st increased. In 1937, the 41st paired with the 3rd Division for Corps maneuvers at Fort Lewis.
During the 14 months prior to the beginning of the World War II, the Division underwent intensive combat-type training and was equipped with the latest, most modern equipment available. By 7 December 1941, the 41st Division was ready. The 41st was the first United States division to deploy overseas to the South Pacific.
The 41st first stopped at Australia for even more training and then proceeded to New Guinea. This time, the 41st became the first American division to meet the Imperial Japanese Army, not in defense, but in an offensive operation. Places with the strange names of Buna, Gona, Sanananda, and Salamaua became battlegrounds in a war with an enemy during which no quarter was given or taken. The Division fought for 76 continuous days in combat against the Japanese at Salamaua. For 26 days only canned "C" rations were available. At the end of this campaign, Tokyo Rose, in her propaganda broadcasts, referred to the 41st as the Butcher Division.
Following the New Guinea campaign, the 41st returned to Australia for rest and re-equipping. In a few weeks, the 41st then made another thrust to the north. Hollandia and Aitape, coastal communities on New Guinea's eastern coast fell, along with the islands of Wakde and Biak. The road continued into the Philippines where more bitter fighting occurred at Palawan, Zamboanga, and the Sulu Archipelago.
After the fall of the Philippines, the Division began training for the attack on Japan itself, but surrender came first. The Division did move to Japan where it occupied the island of Honshu for a few months. Soon after, it was deactivated and the men returned home.