Uhh, I think we already passed Vietnam. First direct ground engagement of NVA and US forces was in late 1965 in the Ia Drang valley (LZ XRAY), the last one was in early 1970 in the A Shau valley (FSB Ripcord). There was a nasty sapper attack in early 1971 at FSB Mary Ann, but that was during the Vietnamization period. Anything before 65 and after 71 was advisory to ARVN.