 The first battle had begun when a pair of companies from the 1st Battalion, 18th Infantry Regiment, had gone to the hamlet of Tân Hiệp (), three kilometers northeast of Dĩ An, to investigate a tip from local authorities about a VC ammunition dump.The troops came under heavy fire from machine guns and recoilless rifles as they tried to enter the hamlet.Thebaud dispatched two more companies of the 1/18th Infantry, along with several troops from the 1st Squadron, 4th Cavalry Regiment and Troop D, 7th Squadron, 1st Cavalry Regiment.