What was the original intent of the war in Vietnam?

They were an ally to the NVA (North Viet Army). The VCs mission was to defeat the US supported South Viet government (Republic of South Vietnam/RVN). The VC had no jets, tanks, nor heavy artillery; they relied upon manpower, small arms, and guerrilla warfare.

Their ally, the NVA, had the tanks, jets, and heavy artillery. The VC gradually lost ground during the war, and were slowly decimated by US/allied firepower over the years; culminating with the communist offensive (Tet) of 1968.

After '68, the NVA shouldered most of the fighting.