Following the Gulf of Tonkin Incident in August 1964, the 9th Marine Expeditionary Brigade (9th MEB) was activated by United States Pacific Command under Admiral Ulysses S. Grant Sharp.

When the Gulf of Tonkin crisis faded, one BLT was sent to Okinawa, another to the Philippines and a third one was served afloat as Special Landing Force of the Seventh Fleet under Admiral Roy L. Johnson.

[1] BGen Frederick J. Karch assumed command of the brigade on 22 January 1965 and 1st and 3rd Battalions, 9th Marines took part in the amphibious landing exercise.

[1] After initial delay because of negotiations with South Vietnamese government, Karch led his brigade ashore on 8 March 1965 on Red Beach.

[1] The unit was reactivated on 1 March 1966 as 9th Marine Amphibious Brigade (9th MAB) on Okinawa, Japan with Colonel Herman Hansen Jr. as temporary commander.

The 9th MAB was assigned to the mission of destroying a VC battalion and elements of a People's Army of Vietnam (PAVN) regiment reported to be operating in Thừa Thiên-Huế Province.

[2] BGen Louis Metzger assumed command of the 9th MAB on 4 January 1967 and led it during Operation Deckhouse V in Bến Tre Province a few days later.

In the six days required to accomplish the Phase II, the battalion killed 78 more VC, destroyed 145 fortifications, and captured an additional five tons of supplies.

On 26 March, after two days of air and artillery preparation, BLT 1/4 broke through two well-prepared defensive trench lines and cleared the interconnecting tunnel system.

The landing exercise at Kin Blue Beach, Okinawa followed during April 1967, where the 9th MAB practiced a combined surface and helicopter assault.

SLF Alpha containing BLT 1/3 and HMM-263 and its mission was to clear Que Son Valley, 25 miles (40 km) southwest of Da Nang, important to the VC as a source of both food and manpower.

The SLF Alpha casualties totaled 55 Marines killed and 151 wounded, but in 16 days of continuous operations the BLT claimed 181 VC dead and 66 prisoners.