> if that doesn't prove that a democracy can fight an unpopular war i don't know what does.

I don't know where you meant to show me that the war was unpopular. Wars are always unpopular to a certain extent, and the propaganda it took to instigate the good and decent American families who sent their sons into some never-heard-of-before jungle simply wore off quickly after those years.

> but in england, the u.s.a., russia, and israel, the head of state is also the head of the military,

Certainly not in Germany! (ノ∀｀)

The ultimate question here is: Are the families of the country who have, during times of peace, become customized to a certain amount of freedom which allows them to do with their lives what they want, willing to support the war of their country / government with the manpower only them can provide. In war, you go and perhaps you will have to kill and perhaps you will have to die, two options which are rather unpopular, especially the latter and in the case of the latter the family will still remain to woe the death of their son (this is a pretty interesting question in how demographics and families with many sons or mainly just one son play into the public opinion on war and its consequences).

Now a war goes on for a few years, to begin with it was against the communist plague but now that a few hundred thousand decent men died and no victory in sight... The war got too unpopular to wage (although I agree it was continued longer than what would have been rational from a PR pov). Dictatorships can always force and lie the people into war pretty easily. In democracies, you cannot force everybody and lying is considerably more difficult.