The Iroquois was originally designated HU-1, hence the Huey nickname, which has remained in common use, despite the official redesignation to UH-1 in 1962. The UH-1 first saw service in combat operations during the Vietnam War, with around 7,000 helicopters deployed.
On 14 January 1966, the 4th Battalion, 9th Infantry Regiment, was relieved from assignment to the 171st Infantry Brigade and assigned to the 25th Infantry Division "Tropic Lightning" at Schofield Barracks, Hawaii. A month earlier these Manchus had been in Alaska preparing for annual winter maneuvers to be conducted in temperatures of 50 below zero. Eight weeks later the battalion was preparing for deployment to the heat and humidity of South Vietnam.
On 29 April, the battalion disembarked the ship General Walker at Vũng Tàu, Vietnam. Within hours of their arrival they found themselves under fire as their convoy made its way to the 25th Division's Củ Chi Base Camp. The next day, a little more than 24 hours after arriving in country, Alpha company engaged the enemy in a firefight – setting the tone of regular contact that would characterize the Manchu experience for the next four and a half years.
Many operations were conducted by company-sized or smaller units but there were also notable larger scale operations in which the entire battalion took part. They included Asheville, Wahiawa, Joliet I and II, Helemano, and Kahana I and II.