In August Lieutenant Colonel Rathbun’s men made a significant modification to their helicopters when they began mounting M-60 machine guns inside the cargo hatch. So as not to obstruct the hatch during loading and unloading phases, the squadron’s metalsmiths designed a flexible mount which allowed the crew chiefs to swing the belt-fed, 7.62mm automatic weapon back into the cabin when necessary. The addition of the machine gun enabled the crew chief to protect the otherwise defenseless helicopter during critical landing and take off phases. Still, the Marine gunners were restricted in their action by MACV’s “rules of engagement” which at this time stipulated that American servicemen could fire only after being fired upon and then only at clearly identified enemy. Intended to prevent offensive combat action by U.S. military personnel operating in Vietnam, these regulations prevented Americans from returning fire except when the enemy was clearly identified.[5-G] Primarily because of these restrictions the Marines seldom employed their M-60s in the heavily populated Mekong Delta. [5-G] The rules of engagement applied to U.S. advisors as well as aviation crews. Although they underwent several modifications during the course of the war, the above definition was virtually unaltered during the period between 1962 and 1964. _Preparations and Redeployment_ In early September General Harkins directed that Colonel Ireland begin planning for the redeployment of his helicopter task unit northward to Da Nang. The shift to I Corps, which had been the subject of much debate prior to SHUFLY’s assignment at Soc Trang, came as no surprise. Shortly after the task unit’s arrival in the Mekong Delta, Colonel Carey accompanied General Condon on a visit to the Army’s 93d Helicopter Company at Da Nang. There they discussed details of the relocation with Army officers. In early July General Harkins set 1 August as the date on which the Marine task unit and the 93d Helicopter Company would switch locations. But personal appeals by General Nghiem, the III Corps commander and his senior U.S. advisor, Colonel Porter, that the Marine helicopters be retained at Soc Trang caused Harkins to postpone the date for the exchange until 15 September.