Marine Medium Helicopter Squadron 561 (HMM-561) was activated on 31 January, 1967, CG 3d MAW message 242223Z Jan 67 to provide refresher training to UH-34 Sea Horse pilots and crews heading to Vietnam.
Marine Medium Helicopter Squadron 561 (HMM-561) was a training squadron of the United States Marine Corps during the Vietnam War. They were active for two years during which time they provided refresher training to UH-34 Sea Horse pilots and crews heading to Vietnam.