"ARVN only faced three large scale assaults during the war. The first one was a disaster for the communists because of massive American support. The second was a disaster for the communists even though American support was limited to air support and a little arty support. ARVN infantry and ARVN armor recaptured all but one town that had been overrun and the communists suffered massive casualties."
Yes, and ARVN (actually the US and ARVN) won those battles because the US military was there to help out--basically by softening up NVA attacks enough with massive air strikes (which conveniently provided the NVA with a good crop of captured US pilots)--so that even the feckless ARVN could defeat them, for the time being at least. The one time ARVN stood alone against an NVA attack it was crushed. South Vietam was rather like a timid child who could never win a fight against a bully unless his dad or big brother was there to back him up. You never saw Israel having to rely on US air strikes to win its battles have you? For that matter, I know of no cases of Russian pilots flying CAS in support of NVA offensives either. The North may have had a Soviet sugar daddy supplying the weapons, but they did ALL the fighting and dying on their own.