The 22nd Marine Regiment was commissioned on June 1, 1942, at Camp Elliot in San Diego, California (Linda Vista tent area).

On Bora Bora the 1st Seabees Detachment (aka Bobcats) and a detachment of A Company 3rd CB had completed their construction projects and were en route to rejoin the Construction Battalion at Noumea when they were diverted and made 3/22.

In November 1943, the Regiment went to Maui, Hawaii and Wallis Island for amphibious warfare training before seeing combat in February 1944.

It was discovered on Guadalcanal that some 1800+ members of the 22nd Marines had been infected while they were training in Samoa in 1942 and 1943 with the slow manifesting tropical disease Filariasis, which causes Elephantiasis.

This greatly reduced the number of experienced Marines, corpsmen, and leaders within the regiment just prior to the Battle of Guam in July.

This was the first Marine Corps unit to formally employ fire team tactics in combat.

[5][6] (1st Provisional Marine Brigade: Navy Unit Commendation, July 21 to August 10, 1944) On July 21, 1944, the 1st Provisional Marine Brigade assaulted and landed south of the Orote Peninsula on Guam, the largest island of the Mariana Islands.

Following the landing they pushed north with the rest of the 6th Marine Division and secured the northern portion of the island.

Commanding officer, Harold C. Roberts, was killed by Japanese sniper on the last day of attack on Sugar Loaf Hill.

Among its duties was training new Marine Corps Officers at The Basic School, Quantico, VA.