After the start of the Korean War, four HMX-1 helicopters were attached to VMO-6 and sent to help the 1st Provisional Marine Brigade at the Battle of Pusan Perimeter in 1950. They were used for battlefield observation and control as well as medical evacuation and the rescue of fliers. During the Chosin campaign they were used for liaison between the different Marine units strung along the western edge of the Chosin Reservoir. The requirements of the Korean War exceeded the Navy's training requirement thus HMX-1 was pressed into service as a training command for the first few years of the war. They trained the nucleus of pilots that would form HMR-161, the first Marine helicopter transport squadron.