year. At best, however, the TK-1 was of only marginal value. The inherent limitations of the UH- 34D, which possessed neither the maneuvera-bility nor the speed to conduct truly effective attacks, reduced the overall value of the system. Because of these limitations the Marines seldom relied solely on the UH-34D for fire suppression during assault missions. The system would eventually be phased out in 1965 with the arrival of Marine jet attack squadrons in Vietnam.
Two improvements, one in the physical facilities available to the task clement and the other in the si2e and composition of its security detachment, were made shortly after the Marines began using the UH- 34Ds in the gunship role. On 25 November, HMM-365 moved its aircraft and maintenance equipment across the airfield into a newly constructed hangar just west of the strip. The second change took place the next day when the security force from the 2d Battalion, 9th Marines was replaced by Company L, 3d Battalion, 9th Marines, reinforced with engineers, 81mm mortar teams, and counter-mortar radar personnel. This adjustment came in response to the reports of the growing Viet Cong threat to Da Nang. Designated the Security Detachment, Marine Unit Vietnam, the 255-man organization was under the command of Major William F. Alsop, the battalion's executive officer. Captain John Sheridan, the company commander, retained tactical control of the infantry unit.
Although responsibility for the overall defense of the Da Nang airstrip still resided with the ARVN, the enlarged security detachment greatly strengthened the Marine defenses within the installation. Major Alsop divided his reinforced rifle company into two groups-one to protect the living compound and the other to defend the flight line and the new hangar. Around the living compound the engineers constructed a complex of machine gun positions, mortar pits, and ammunition bunkers. A barricade was also erected at a gate near the Marine compound which previously had been open and manned only by Vietnamese sentries. Strong defensive positions were also constructed around the task element's new hangar and flight line. This network included fox holes, barbed wire, and cleared fields of fire. As an added precaution. Company L maintained a reaction force at the living compound. This force was prepared to board trucks and rush to reinforce the critical defenses around the aircraft and maintenance facilities in the event of an enemy ground attack.5
Despite the stronger defenses and the presence of the larger Marine infantry force, several security-related problems were still unsolved. One which remained outside of Colonel King's influence was the laxity of the ARVN sentries around the outer perimeter who sometimes allowed Vietnamese civilians to wander into the installation. Another was that a small village close to the Marine compound, but outside the perimeter fence, still harbored an occasional sniper. The task element commander had lodged repeated complaints about both situations with the appropriate South Vietnamese authorities but no action had been taken to eliminate them. In spite of these minor sources of irritation, the recent changes in its defenses greatly enhanced the task element's ability to protect itself against Communist ground attacks.
Action as the Year Ends
While Company L was developing defensive positions at the airbase, HMM-365's crews continued to provide support for both flood relief and military operations throughout I Corps. On 7 December, 17 Marine helicopters and eight Army UH-1B transports were called upon to help trap a Viet Cong force known to be hiding in a village less than five miles west of Da Nang. Code named DA NANG SIX, the operation began at daybreak when the American helicopters lifted 240 men of the llth ARVN Ranger Battalion into the objective area. Two UH-1B gunships teamed with two armed UH-34Ds to suppress ground fire that erupted as the first wave of transport aircraft began their approach to the landing zone. One Army gunship sustained minor damage when hit three times during the exchange of fire. After the enemy had been silenced, the landing proceeded without incident and the Vietnamese rangers quickly secured their objective. In the process, nine Viet Cong were killed and four others captured along with nine rifles and one automatic weapon. Successful though it was, the action on the outskirts of Da Nang confirmed previous reports that the Communists were tightening their grip on Quang Nam Province.6
Page 164 (The Advisory & Combat Assistance Era: 1954-1964)