“I had always suspected the VC and NVA combined forces. Is this true?”
IIRC the NVA convinced the Viet Cong into leading the Tet assaults on the cities of South Vietnam.
And the result was that the Viet Cong were nearly wiped out in the process, with the center of gravity of the war then shifting to NVA regulars.
I doubt that Hanoi was all that unhappy about the outcome. Their goal was to conquer South Vietnam for themselves and they may have seen the VC as a potential rival that they would need to push aside anyway.
Walter Cronkite deserves an honorable mention from Hanoi for his useful idiot role in convincing the American public that Tet was a Communist victory, and “proof” that the South Vietnamese people didn’t care about defending their country from conquest.
“I doubt that Hanoi was all that unhappy about the outcome. Their goal was to conquer South Vietnam for themselves and they may have seen the VC as a potential rival that they would need to push aside anyway.”
My recollection of events after the fall of Saigon in ‘75 is that the VC were really treated no better than the ARVN’s. A typical commie strategy was to consolidate power once victory is achieved, and this meant neutralizing rivals.