HMM-163 participated in its first combat mission as a squadron on 1 August when it joined the Army’s 57th Helicopter Company in a coordinated troop lift. Like their predecessors, “Rathbun’s Ridge Runners” maintained a brisk pace of operations during the weeks following their initial assignment. Shortly after its first troop lift, the squadron participated in a 2,000-man South Vietnamese spoiling operation in An Xuyen, South Vietnam’s southernmost province. Anticipating a major Viet Cong offensive in the four southern provinces, III Corps authorities moved their headquarters to Soc Trang and established a forward command post at Ca Mau. The Vietnamese Air Force then positioned a composite detachment of four AD-6 Skyraiders (single-engine, propeller-driven attack bombers built by Douglas), two T-28s, and a number of H-34 helicopters (the U.S. Army, Air Force, and VNAF version of the HUS) at Soc Trang to support the operation. Joined by the VNAF H-34s, the Marine squadron conducted numerous troop lifts during the week-long operation. At the end of the action the ARVN reported 84 Viet Cong killed, another 30 captured, and the confiscation of nearly 15,000 pounds of arms, ammunition, and explosives. The first Marine helicopter loss in Vietnam occurred during the operation when a VNAF fighter careened off the runway and damaged a parked HUS to the extent that it could not be repaired. Marine mechanics stripped undamaged parts from the helicopter for use as replacements.[5-F] [5-F] Marine helicopters lost in Vietnam during the 1962–1964 period were replaced by new ones airlifted from Okinawa by U.S. Air Force C-124 Globemaster transports. By replacing aircraft losses on a one-to-one basis the task unit was able to maintain a level of 24 helicopters except for brief periods. HMM-163 suffered its first aircraft damage as a result of combat a few day’s later on 18 August during a mission led by Lieutenant Colonel Rathbun. Fourteen HUSs arrived at a prearranged pickup point to rendezvous with an ARVN infantry force but the Marine pilots discovered that the unit had not appeared. One crewman then reported having seen some ARVN troops about a half mile away from the landing zone. At this juncture, a white smoke signal appeared at approximately the same location that the Marine had observed the South Vietnamese troops. Lieutenant Colonel Rathbun and his wingmate, assuming that the smoke marked the actual pickup point, took off to investigate the area. While making a low pass over the smoke signal, the squadron commander’s helicopter was hit several times by small arms fire which severed the rudder control cable and punctured the main rotor transmission. The loss of oil required Rathbun to make a forced landing on a nearby road. After mechanics had been flown in and repairs had been accomplished, the helicopter was flown to a secure area.