1st Squadron, 4th Cavalry (1-4 Cavalry, popularly called "Quarterhorse") was assigned to be the divisional reconnaissance squadron of the 1st Infantry Division based at Di An. It arrived at Vung Tau on 7 October 1965, making it the first element of the 4th Cavalry to deploy to Vietnam.
The 1st Squadron participated in eleven campaigns of the Vietnam War from 20 October 1965 to 5 February 1970.