In September 1966, the White Knights deployed to the Republic of Vietnam, where they were assigned to Marine Aircraft Group 36, 1st Marine Aircraft Wing. From October 1966 to August 1969, the squadron operated from Ky Ha, Hue/Phu Bai, the USS Valley Forge (CV-45), the USS Tripoli (LPH-10), Marble Mountain area near Da Nang, and from the USS Tarawa (LHA-1). On June 6, 1968, HMM-165 had two of their CH-46As shot down in the vicinity of Khe Sanh. There were no deaths on the first incident but the second crash which occurred at LZ Loon, southeast of Khe Sanh, resulted in the death of 12 of the 23 Marines on board. In August 1969, the squadron redeployed to Okinawa where it was reassigned to Marine Aircraft Group 15 of the 9th Marine Amphibious Brigade. In December 1969, the squadron again became part of Marine Aircraft Group 36. During the early 1970s, HMM-165 participated as part of the Special Landing Force in support of activities in the Republic of Vietnam. During July and August 1972, the White Knights took part in Philippine flood relief operations, flying in food and supplies to local populations. At the end of April 1975, helicopters of HMM-165 played a key role in the evacuation of Saigon, Operation Frequent Wind. On 30 April 1975, under direct orders from President Gerald Ford, the crew of Lady Ace 09 evacuated U.S. ambassador Graham Martin from the US Embassy, Saigon, marking the official end of American involvement in the Vietnam War.