On 19 May 1971, the commander of 2/1, Lt. Col. Roy E. Moss, his command group, and the battalion colors boarded planes bound for Camp Pendleton. The last 186 members of the battalion sailed from Da Nang aboard the USS Denver on 1 June.  With all of its combat and support units gone, the 3d MAB turned over its remaining facilities to either the U.S. Army or the ARVN. The 3d Marine Amphibious Brigade was formally deactivated on 27June 1971. General Armstrong had departed for Hawaii with a dozen members of his staff the previous day. The balance of the brigade staff followed over the next few days.

The six-year U.S. Marine Corps involvement in the long, often frustrating, occasionally victorious war in South Vietnam was nearly at an end. With all Marine ground combat, aviation, and support units redeployed, the only Marines remaining in South Vietnam were the approximately 550 officers and men serving as embassy guards, on the MACV staff, or as advisers to the South Vietnamese Marine Corps