On July 15, 1966, during the first day of Operation Hastings, HMM-265 had two of its helicopters crash. The first crash was caused when a CH-46A struck a tree during the initial insert of Marines from 3rd Battalion, 4th Marines and the second occurred later that evening when aircraft EP-171 was hit at by 12.7 mm fire resulting in the death of 13 Marines. In addition to daily missions transporting Marines and cargo, HMM-265 and its Sea Knights flew in support of Operation Macon from July 4 through October 27, 1966. HMM-265 along with HMM-164 conducted multiple battalion insertions to allow the 3rd Marine Division to conduct multiple search and destroy missions in the An Hoa region. 12th Marines artillery and Marine A-4 Skyhawks fired on landing zones prior to the CH-46s landing.