 Towards the end of 1964 , the National Liberation Front commenced a series of large @-@ scale military operations against the Army of the Republic of Vietnam , as ordered by the North Vietnamese government . As part of their Winter @-@ Spring Offensive , the Viet Cong unleashed its newly created 9th Division against the South Vietnamese forces at Bình Giã , fighting a large set @-@ piece battle for the first time . Over a period of four days , the Viet Cong 9th Division held its ground and <unk> the best units the South Vietnamese army could send against them , only breaking after intense attack by U.S. bombers . 
