 The defense of the Capital Military Zone was primarily a South Vietnamese responsibility and it was initially defended by eight ARVN infantry battalions and the local police force . By 3 February they had been reinforced by five ARVN Ranger Battalions , five Marine Corps , and five ARVN Airborne Battalions . U.S. Army units participating in the defense included the 716th Military Police Battalion , seven infantry battalions ( one mechanized ) , and six artillery battalions . 
