Under the Geneva Accord of 1954, Vietnam had been temporarily divided into northern and southern parts, pending the results of elections which were to be held in 1956 to reunify the country. The victorious Viet Minh controlled the north, whereas President No Dinh Diem controlled the south.
Unfortunately, the Vietnamese elections were never held, and a train of events was initiated which ultimately led to the American involvement in Southeast Asia.
The Diem regime in the South became increasingly dictatorial, corrupt, and inept, and a series of revolts against it broke out. Initially, these were strictly indigenous actions, with very little support from the North. Many of the rebels weren't even Communists, but were instead members of the Hoa Hao and Cao Dai religious sects. However, there were elements of the southern Communist-oriented Viet Minh who had stayed in the south after the Geneva accords and who had joined the rebellion. In May of 1959, the government of the Democratic Republic of Vietnam (North Vietnam) decided to provide assistance, training, and troops to the growing rebellion in the South. In late 1960, the National Liberation Front was created, and its military arm became known as the Viet Cong. The term Viet Cong was supposedly an abbreviation of Viet Nam Cong San or Vietnamese Communists, a derogatory term used by No Dinh Diem for the groups of Communist Viet Minh rebels that had stayed in the South after the Geneva accords and which had been causing trouble for the government
By the time that President John F. Kennedy entered office in 1961, the Diem regime was in deep trouble. At that time, the only American presence in the country was a small Military Assistance Advisory Group which provided training and assistance to the South Vietnamese military. In the spring of 1961, anxious to prevent yet another nation in Southeast Asia from coming under Communist control, President Kennedy ordered that more US military advisors be sent to provide additional assistance and support to the regime in South Vietnam.
At that time, the South Vietnamese Air Force was equipped with Grumman F8F Bearcats that had been inherited from the French, plus some AD Skyraiders and T-28 Trojans provided by the US. The US government decided to provide some additional strike aircraft to South Vietnam, and 27 B-26 Invaders were taken out of storage at Davis Monthan AFB and reconditioned at Hill AFB. The 4400th Combat Crew Training Squadron was to accompany the B-26s to South Vietnam to help train local crews.
The crews of the 4400th began deploying to Vietnam in early November of 1961, even before the B-26s were ready for delivery. The deployment was given the code name of Project Farm Gate. Their aircraft were initially four SC-47s and eight T-28s. In order to conceal the American involvement in the effort, the aircraft were painted in Vietnamese national insignia. Officially, the initial mission of the Farm Gate detachment was to provide training for the VNAF, and whether or not the US crews were to participate in actual combat was left ambiguous. In reality, it was expected from the start that American crews would be flying most of the actual combat missions, with Vietnamese often riding along.
The first Farm Gate combat action began with a few T-28 missions flown in support of VNAF Skyraider strikes, plus a few SC-47 and T-28 reconnaissance missions flown to monitor the junk traffic along the Vietnamese coast. The B-26s did not arrive until a few weeks later, the first examples being former Mill Pond aircraft that had been withdrawn from Laos. The B-26s were listed as "RB-26s" in official press releases, implying that they were reconnaissance aircraft and not true military aircraft the introduction into Vietnam of which would be in violation of the Geneva Accords.
During the first quarter of 1962, the number of combat missions steadily increased. Most of the missions involved air strikes against Viet Cong positions throughout South Vietnam. In April of 1962, the 4400th CCTS was renamed the 1st Air Commando Group. By this time, there had been a number of press reports that US pilots were flying combat missions in Vietnam. The official cover story was that these missions were strictly training missions, with joint US/Vietnamese crews aboard the aircraft. In fact, very little training was actually carried out, and to satisfy the demand for a joint US/Vietnamese crew, a member of the VNAF would often ride along on missions in the jump seat behind the pilots.
Four more B-26s arrived in the summer of 1962, and ten more B-26s arrived in early 1963. Unlike the earlier B-26s (which had all come from other classified projects), these new ones had been through a complete IRAN at Hill AFB. Two of them were RB-26Ls which were equipped with nighttime reconnaissance capability. By April of 1963, Farm Gate strength stood at 12 B-26Bs and 13 T-28Bs. Four more B-26s were received in mid-1963. These were survivors of the abortive 1958 CIA operation in Indonesia.
By February of 1963, it was well known to almost everyone that Farm Gate was a purely American operation, and the classified nature of the program was officially dropped in the spring. On July 8 the unit was reformed as the 1st Air Commando Squadron (Composite) of the 34th Tactical Group. The national insignia were repainted to resemble official USAF markings, and operations continued as before.
By the end of 1963, the heavy underwing loads used by Farm Gate B-26s had imposed high forces on the wings, and the aircraft were beginning to show signs of fatigue. After a B-26 had lost a wing during a mission on August 16, 1963, strict limitations had to be imposed on the maneuvers allowed during combat missions. When a second B-26 was lost statesite while pulling out of a strafing run during a firepower demonstration at Eglin AFB in February of 1964, it was concluded that the B-26 was too old for any more active duty, and the decision was made to withdraw the B-26 from combat altogether. From that day on, the Farm Gate B-26s were effectively grounded.
The Farm Gate B-26s were flown to Clark Field in the Philippines in April of 1964. Most of them were scrapped there in late 1964 or early 1965, but four were to later to become involved in the Congo operation.
The last B-26Bs in USAF squadron hands had been flying with the 605th Air Commando Squadron at Howard AFB in the Canal Zone. They were retired to Davis Monthan AFB on October 12, 1964, ending the front-line service of the B-26B/C with the USAF. All Invaders serving with the USAF after that date were converted B-26Ks.