Easter Offensive - Air Support, Freedom Train, and Linebacker

Air Support, Freedom Train, and Linebacker

The North Vietnamese had timed their offensive well by having it coincide with the end of the annual winter monsoon when low cloud cover and rain provided a blanket under which the offensive could proceed without interference by allied aerial attack. Air strikes were possible only by all-weather fighters or bombers, which could deliver their ordnance accurately through the cloud cover by radar direction or LORAN.

These missions were conducted by aircraft assigned to the U.S. Seventh Air Force and Seventh/Thirteenth Air Force in South Vietnam and Thailand or by the U.S. Navy's Task Force 77, offshore in the South China Sea. Besides the weather the most serious problem facing the Americans was that the drawdown of U.S. forces during the previous four years had included valuable ground support aircraft and their maintenance crews. By the spring of 1972, the U.S. Air Force had only three squadrons of F-4 Phantoms and one of A-37 Dragonflys available in the Republic of Vietnam, a total of 76 aircraft. Another 114 fighter-bombers were stationed at various bases in Thailand. 83 B-52 Stratofortress heavy bombers were located at U-Tapao RTAFB and at Andersen Air Force Base, Guam. Task Force 77 had four carriers assigned to it, but only two, Coral Sea and Hancock were on station at the onset of the offensive. Their air wings totaled 140 strike aircraft.

To rectify the aircraft shortage, from 7 April to 13 May 176 F-4s and 12 F-105 Thunderchiefs were transferred from air bases in the Republic of Korea and the continental U.S. to Thailand during Operation Constant Guard I-IV. Between 5 February and 23 May, the Strategic Air Command (SAC) reinforced Guam during Operation Bullet Shot with a further 124 bombers, bringing the total available in-theater to 209. The Seventh Fleet was also beefed up by the addition of four aircraft carrier groups, including those of the Kitty Hawk, Constellation, Midway, and Saratoga. This made four carriers available at any one time to conduct aerial operations. The South Vietnamese Air Force (VNAF) at this time consisted of nine squadrons of A-1 Skyraiders, A-37s, and F-5 Freedom Fighters, a total of 119 strike aircraft. There were also two squadrons of AC-47 or AC-119 fixed-wing gunships, totaling of 28 aircraft.

The weather conditions made early ground support haphazard, and these difficulties were compounded by North Vietnamese anti-aircraft units, which advanced behind the front line elements. PAVN moved 85 and 100 mm radar-directed batteries south of the DMZ and, on 17 February, 81 SA-2 Guideline missiles were launched from the DMZ area, downing three F-4s. This heralded the farthest southern advance of SA-2 units thus far during the conflict. This classic high-low anti-aircraft coverage made aerial attacks extremely hazardous, especially when it was enhanced by the new shoulder-fired Grail.

The loss of the northern firebases early in the offensive in I Corps made U.S. naval gunfire the primary source of artillery support in that area. U.S. Marine Corps gunfire observers were then assigned to fly with forward air controllers, providing coordinates for shore targets. At the height of the offensive three U.S. cruisers and 38 destroyers were providing naval gunfire support.

With clearing weather the number of aircraft sorties soared. Between April and June there were 18,000 combat sorties flown to support the ARVN defense, 45 percent by the U.S. Air Force, 30 percent by the Navy and Marine Corps, and 25 percent by the VNAF. B-52s flew an additional 2,724 sorties. Ten U.S. and six VNAF aircraft were lost to SAM or anti-aircraft fire.

On 4 April, reacting to the fierceness of the offensive, President Nixon authorized tactical airstrikes from the DMZ north to the 18th parallel, the southern panhandle of North Vietnam. This supply interdiction effort was the first systematic bombing carried out in North Vietnam proper since the end of Operation Rolling Thunder in November, 1968. Airstrikes north of the 20th parallel were authorized on 5 April under the cover name Operation Freedom Train. The first B-52 strike of the new operation was conducted on 10 April. President Nixon then decided to up the ante by targeting Hanoi and Haiphong. Between 1 May and 30 June, B-52s, fighter-bombers, and fixed-wing gunships had carried out 18,000 sorties over North Vietnam and suffered 29 aircraft losses.

On 8 May Nixon authorized the launching of Operation Pocket Money, the aerial mining of Haiphong and other North Vietnamese ports. Nixon had taken a gamble that Soviet Union, with which he was conducting negotiations for a strategic arms limitation treaty (SALT I), would withhold a negative reaction in return for improved relations with the West. He was correct. The People's Republic of China also muted any overt response to the escalatory measures for the same reason. Emboldened, Nixon decided to launch Operation Linebacker a systematic aerial assault on North Vietnam's transportation, storage, and air defense systems on 10 May. During Linebacker, the U.S. Air Force, Navy, and Marine Corps lost 134 aircraft while their North Vietnamese opponents lost 54.