The Headquarters was concurrently initiated at Birmingham, Alabama, with Reserve personnel previously assigned to the demobilized XIV Corps (RAI).

The XIV Corps was not activated prior to World War II and was located in Birmingham as of 7 December 1941 in a reserve status.

From air fields guarded by the XIV Army Corps, Allied aircraft began the neutralization of the enemy's vital Munda airfields on New Georgia.

American and New Zealand aircraft operating from the Munda field began the neutralization of Kahili and other enemy airfields in Bougainville.

In the Bougainville campaign, the 37th and Americal Divisions, and two battalions of the Fiji military forces, were the principal combat units of XIV Corps.

The landing was made without ground opposition as the Japanese garrison, completely surprised, fled three days before S-Day at the start of an intensive naval and aerial bombardment.

Meeting sporadic resistance, the corps drove rapidly south towards Manila, capturing successively Binmaley, San Carlos, Malasiqui and Tarlac.

Meanwhile, the 6th (Red Star) Infantry Division joined XIV Corps on 17 February and attacked well fortified enemy forces in the Shimbu Line east of Manila.

The cleanup of Southern Luzon with the 1st Cavalry and the 11th Airborne comprising major corps units was begun 15 March, and by 20 May the area was declared free of Japanese organized resistance.