IX Corps

Original WWII shoulder badge of the IX Corps. 

Corps headquarters was finally activated on October 24, 1940, at Fort Lewis, Washington, as part of a major buildup of the United States military in response to conflicts around the world. He immediately began training combat units in preparation for deployment. A year later, IX Corps assumed command of the Camp Murray staging area in Washington, responsible for training Army National Guard forces in addition to its responsibilities for training active duty units and reserve.

Following the Japanese attack on Pearl Harbor in late 1941, IX Corps was assigned defensive duties on the west coast of the United States, particularly the central and northern coastal regions. The corps oversaw defenses on the West Coast for most of the war, but in 1944 it was moved to Fort McPherson, Georgia, in preparation for overseas deployment.

The corps trained at Fort McPherson in preparation for deployment to the Pacific theater of operations. On September 25, 1944, the corps closed its headquarters at Fort McPherson and moved to Hawaii. Upon arrival in Hawaii, the IX Corps was placed under the command of the Tenth United States Army. Under the Tenth Army, the IX Corps was given two missions. In 1944, this mainly involved formulating plans for an invasion of the Japanese-controlled coastal regions of China. Later in 1944 and early 1945, he was tasked with preparing the remainder of the Tenth Army for movement to Okinawa in preparation for an invasion of the island, which was launched in April 1945.

When Army General Douglas MacArthur assumed overall command of Pacific forces, IX Corps was transferred to Leyte in the Philippine Islands and was assigned to the Sixth United States Army in July 1945. At Leyte, the corps was tasked with planning Operation Downfall. , the invasion of mainland Japan, more precisely of the island of Kyushu. He was also responsible for planning the occupation once Japan surrendered. IX Corps was designated as one of four Corps under the command of Sixth Army, with a strength of 14 divisions. Along with the 77th Infantry Division, 81st Infantry Division, and 98th Infantry Division, a force of 79,000, IX Corps would serve as Sixth Army's reserve force during the initial invasion. Before the assault could be launched, Japan surrendered in August 1945, following the use of nuclear weapons on Hiroshima and Nagasaki.