Marine Medium Helicopter Squadron 365 was established on July 1, 1963 at Marine Corps Air Facility Santa Ana, California.
Flying UH-34Ds, the squadron's mission was to provide assault transport of troops and cargo in support of Fleet Marine Forces during ship-to-shore movements.
HMM-365 was reassigned to Marine Corps Air Station Futenma, Okinawa in August 1964 in preparation for the squadron's deployment to the Republic of Vietnam.
The squadron arrived at Da Nang Air Base on October 7, 1964 and immediately began performing re-supply missions in support of Operation Shufly.

On October 11, the newly arrived Marine pilots and aircrews were involved in their first firefight when 8 UH-34Ds drew Viet Cong fire while landing a 112-man Vietnamese unit in the hills 10 miles (20 km) west-southwest of Tam Ky. On October 26, the Blue Knights suffered their first combat casualties when a copilot and crew chief were wounded by Viet Cong small arms fire while their helicopter was approaching an enemy contested landing zone 10 miles (20 km) southwest of Tam Ky. The pilot was able to return the damaged aircraft to Tam Ky and land safely.
 In early November, at the height of the monsoon season, Typhoon Iris struck the Vietnamese Coast.
The hazardous weather conditions caused flight operations to be suspended except for emergency medical evacuations.
When flight operations resumed on November 10, the crews concentrated on rescuing Vietnamese civilians from the inundated coastal plains.
Between 1700 and 1900 on their first day of flood relief operations, HMM-365 rescued 144 flood victims.
Many of the rescues were accomplished by hoisting individuals from precarious positions in trees or on rooftops while being subjected to sporadic Viet Cong harassing fire.
At the end of a 72-hour time period the Blue Knights had successfully rescued over 1,500 flood victims.

Meanwhile, other squadron members were modifying three helicopters to carry a new weapons system.
The TK-1, an externally mounted combination of M-60 machine guns and 2.75-inch (70 mm) rocket launchers, that was first used in support of a Tiger Flight mission conducted just south of the Song Thu Bon, about 17 miles (27 km) from Da Nang.
Two armed UH-34Ds expended 90 rockets and 500 rounds of 7.62 mm ammunition on enemy positions during pre-landing strikes.
The squadron executed similar operations the following day.

The squadron remained at Da Nang until February 1965.
 They embarked aboard the USS Princeton on March 7, 1965 to support the 7th Fleet's Special Landing Force until April 27.
HMM-365 returned to Da Nang on May 15 and remained until relieved in August 1965.
The squadron flew over 12,000 mishap-free hours in support of heavy combat operations.
On September 1, HMM-365 was reassigned to Marine Aircraft Group 26, MCAS New River, North Carolina.
For its service in Vietnam, the squadron was awarded the Presidential Unit Citation and the Navy Unit Commendation.

In 1966, the squadron conducted relief operations in the Dominican Republic and Haiti following Hurricane Inez.
 In March 1967, HMM-365 received its first CH-46 Sea Knight .
The transition was complete by late June.
In January 1970, the squadron received eight new CH-46B aircraft in preparation for its upcoming deployment to the Caribbean.
That June, the squadron flew disaster relief operations in Peru following an earthquake.

On March 1, 1971, HMM-365 was deactivated.
Marine Medium Helicopter Squadron 365 was established on July 1, 1963 at Marine Corps Air Facility Santa Ana, California. Flying UH-34Ds, the squadron's mission was to provide assault transport of troops and cargo in support of Fleet Marine Forces during ship-to-shore movements. HMM-365 was reassigned to Marine Corps Air Station Futenma, Okinawa in August 1964 in preparation for the squadron's deployment to the Republic of Vietnam. The squadron arrived at Da Nang Air Base on October 7, 1964 and immediately began performing re-supply missions in support of Operation Shufly.
On October 11, the newly arrived Marine pilots and aircrews were involved in their first firefight when 8 UH-34Ds drew Viet Cong fire while landing a 112-man Vietnamese unit in the hills 10 miles (20 km) west-southwest of Tam Ky. On October 26, the Blue Knights suffered their first combat casualties when a copilot and crew chief were wounded by Viet Cong small arms fire while their helicopter was approaching an enemy contested landing zone 10 miles (20 km) southwest of Tam Ky. The pilot was able to return the damaged aircraft to Tam Ky and land safely.  In early November, at the height of the monsoon season, Typhoon Iris struck the Vietnamese Coast. The hazardous weather conditions caused flight operations to be suspended except for emergency medical evacuations. When flight operations resumed on November 10, the crews concentrated on rescuing Vietnamese civilians from the inundated coastal plains. Between 1700 and 1900 on their first day of flood relief operations, HMM-365 rescued 144 flood victims. Many of the rescues were accomplished by hoisting individuals from precarious positions in trees or on rooftops while being subjected to sporadic Viet Cong harassing fire. At the end of a 72-hour time period the Blue Knights had successfully rescued over 1,500 flood victims.
Meanwhile, other squadron members were modifying three helicopters to carry a new weapons system. The TK-1, an externally mounted combination of M-60 machine guns and 2.75-inch (70 mm) rocket launchers, that was first used in support of a Tiger Flight mission conducted just south of the Song Thu Bon, about 17 miles (27 km) from Da Nang. Two armed UH-34Ds expended 90 rockets and 500 rounds of 7.62 mm ammunition on enemy positions during pre-landing strikes. The squadron executed similar operations the following day.
The squadron remained at Da Nang until February 1965.  They embarked aboard the USS Princeton on March 7, 1965 to support the 7th Fleet's Special Landing Force until April 27. HMM-365 returned to Da Nang on May 15 and remained until relieved in August 1965. The squadron flew over 12,000 mishap-free hours in support of heavy combat operations. On September 1, HMM-365 was reassigned to Marine Aircraft Group 26, MCAS New River, North Carolina. For its service in Vietnam, the squadron was awarded the Presidential Unit Citation and the Navy Unit Commendation.
In 1966, the squadron conducted relief operations in the Dominican Republic and Haiti following Hurricane Inez.  In March 1967, HMM-365 received its first CH-46 Sea Knight . The transition was complete by late June. In January 1970, the squadron received eight new CH-46B aircraft in preparation for its upcoming deployment to the Caribbean. That June, the squadron flew disaster relief operations in Peru following an earthquake.
On March 1, 1971, HMM-365 was deactivated.
VMM-365