After the Nazis came to power, what was it like for the already existing German military. Were there a large scale reshuffling? Did the military as a whole accept the Nazis (and the rule of Hitler specifically) with open arms? And did any high ranking German generals or admirals refuse and what became of them?
Though more can always be said, I think you may find my recent answer to a similar question helpful for pointing you in the right direction. In short, the aims of Nazism (especially the aims most apparent in the early-mid 1930s) aligned with some of the aims of more traditional German conservativism and the military establishment - departure from Versailles terms, restoration of German pride and strategic preeminence in Central Europe, reclamation of lost territory, to name a few - and so much of the conservative military establishment went right along as fellow travelers, even if they themselves were not Nazis. The military pre-Hitler was the Reichswehr, limited by the Treaty Versailles to about 100,000 men. The Reichswehr, in particular the officer corps, formed an influential nucleus for the new German military; however, the vast majority of the Wehrmacht's men under arms by the beginning of the war were by necessity new recruits.