At what point does a General cease to be a soldier and become a politician himself, 2*,3*,4* ?
I don't think anyone advances beyond 1 star without being as much a politician as a military man, and the further up the star tree, the more the politician and the less the soldier is the tacit requirement.
To oversimplify: 1 star -50/50, 2 star, 70/30, 3 star, 80/20. Top job? as high as 90/10, I suspect. We just have to consider ourselves lucky that that 10% still represents quite a lot of soldierly knowledge and ability... in some, (if unfortunately not all), cases. David Petraeus immediately comes to mind.
I can't imagine the frustration that almost every senior officer must feel when dealing with the current Afghan government, although I expect we'll be treated to some very illuminating memoirs after everyone who can sue is safely dead and buried.