On 10 November 1940 President Roosevelt federalized the National Guard, and on 18 November 1940 the 112th was posted to
Fort Bliss. The 112th's sister regiment in the brigade, the
124th Cavalry was the last of the cavalry regiments to give up their horses and was later sent to Burma. The regiment patrolled the Mexican border until being shipped to
New Caledonia on 8 July 1942 arriving on 11 August 1942. They were assigned to the
Americal Division under General
Alexander Patch. The Australian horses were shipped to
Burma and assigned to Chinese forces who mistreated them. In 1944 the
Walers rejoined the American Army being assigned to
Merrill's Marauders. During the heavy fighting on
Guadalcanal, General
Alexander Vandegrift of the
1st Marine Division sent an urgent request for
machetes for his Marines. General Patch took the sabers of the regiment, cut them down and sent them to the Marines for
jungle warfare use. After extensive training the 112th made its first
amphibious landing at
Woodlark Island as part of
Operation Chronicle on 30 June 1943. The landing was unopposed, and the cavalrymen established a defensible perimeter to protect
Seabees building an airstrip on the island. The regiment was sent to
Goodenough Island for training and became part of Task Force Director in preparation for its first action,
Operation Director the
Battle of Arawe. The 112th set sail on , and the
high speed transports and . On 15 December 1943 the regiment landed in three separate amphibious operations on
New Britain. One of these landings involved Troop A of the 2nd Squadron landing in rubber boats off
Sands against fierce defense that sank all but three of the boats. The destroyer sailed close as possible to the enemy defenders to shell them and rescue the survivors of A Troop. Troop B landed at
Pilelo Island from
Humphreys in 15 rubber boats on the same day. When meeting resistance from Japanese troops in caves, Troop B destroyed one with a
bazooka and one with a
flamethrower the first use of the weapon in the
South West Pacific area. The main landings were from
amphibious tractors launched from
Carter Hall and landing craft from
Westralia. In this landing the 112th Cavalry were the first to use the rocket firing
DUKWs. After linking up with the 1st Marine Division, the 112th was assigned to the
32nd Infantry Division in
Aitape Papua New Guinea. The regiment fought in the
Battle of Driniumor River for 51 days taking 62% casualties. Two of the regiment's
second lieutenants,
Dale Eldon Christensen and
George W. G. Boyce Jr. were awarded the
Medal of Honor for their actions during this period. On 1 October 1944 the 112th Cavalry was combined with the 114th Field Artillery Battalion became the 112th Regimental Combat Team (RCT) and departed Aitape for
Leyte in the
Philippines on 31 October 1944. The 112th RCT was attached to the
1st Cavalry Division for the
Battle of Leyte and
Battle of Luzon. Following the Japanese surrender, the 112th landed in Japan for Occupation Duties on 3 September 1945. During World War II the 112th Cavalry served 434 days in combat. They were the first U.S. Army unit in the Southwest Pacific to use bazookas and flame throwers against enemy defenses and first used rocket firing DUKWs in amphibious assaults. The 112th were the first unit in the Philippines to use
helicopters to evacuate their wounded. Two of the regiment's late replacements authored books after the war ended.
Norman Mailer wrote
The Naked and the Dead, and
Francis Gwaltney authored
The Day the Century Ended, later filmed as
Between Heaven and Hell. ==Postwar==