Today, the US designed TOW missile is almost ubiquitous, being used by more countries than you can shake a stick at. It’s also in use by the Free Syrian Army rebels in that nasty little civil war they have going on.
But in 1972, the TOW was brand spanking new. The Army had its eye on the stupendous fleets of Warsaw Pact tanks in Europe, and wanted to get a good idea of just how well TOW would work, particularly mounted on a helicopter.
As it happened, the famous Easter Offensive of the Vietnam War broke out just about the same time that TOW was ready for operational testing. While we generally think of the Vietnam War as one fought by infantry supported by artillery in jungles or rice paddies, there was a shift in the Easter Offensive. The US had spent the years from 1964 to 1972 perfecting counter-insurgency warfare. But the the North Vietnamese Army in 1972 launched an entirely conventional, mechanized, invasion of South Vietnam. Large numbers of tanks, APCs and fleets of trucks supported the invasion. The Army of the Republic of Vietnam was ill equipped to deal with that mechanized threat. Only the prompt and massive application of American airpower staved off the invasion.
And one small part of that was the combat debut of TOW, mounted on UH-1B gunships.
The success of the interim XM-26 TOW armament system would inspire the Army to mount a similar system on its fleet of AH-1 Cobra gunships, which would be the primary attack helicopter in the Army fleet until introduction of the AH-64 Apache and its Hellfire missile in the late 1980s.