It's not my history that's lack, it's my bloody memory
Historically - and this is the position I'm taking to try and make the point - Indo-China has been in turmoil for hundreds and hundreds of years. The Chinese and Vietnamese (I'll use that term for convenience) had been at it well before the French turned up. Ho - now I'm going from memory of my reading about him so this could go anywhere - was a patriot who wanted the Japanese out of his country and then the French.
My point is that Ho regarded South Vietnam as being part of his country. From his perspective and that of his colleagues it wasn't an invasion (although in the eyes of the international community outside of China and the Soviet Union it was). What drove them was a sense of liberation from colonial and then imperialist powers.
This thread is about motivation, about why guerilla insurgencies are difficult for conventional forces to deal with. Part of the problem has to do with the sheer difficulty of fighting guerilla forces. Conventional forces - as we know - find it difficult to fight guerillas for various reasons. But even when guerilla tactics are used against guerillas I'm not sure if it works. I remember reading many years ago about the US Army Special Forces working with the Montagnard people in Vietnam. I don't know if it was very successful but it was an example of fighting fire with fire I suppose.
There are some examples of situations where insurgents may have not been as successful as they woudl have hoped. The French Resistance in WWII fought the Vichy government and the German occupiers both. Despite much heroism shown by the resistance I'm not sure if they were able to make a dent on the Vichy and Germans. If the D-Day Invasion hadn't been such a stunning success (or if it had never happened or if Operation Sea Lion had been successful itself) I wonder if the resistance would have eventually faded when the light of defiance had faded. Of course the Vichy and German forces were in a good position to defeat the resistance and, as we know, they were absolutely ruthless.