It is entirely untrue that "Bush's grandfather helped bankroll Hitler." To piece together a very tenuous connection like this is deceptive and fraudulent, much like Al Gore's beard or Michael Moore's stairmaster.
Prescott Bush merely served on the board of directors of Brown Bros Harriman, as many bankers and politicians did back then, as a kind of sinecure.
Board directors meet 4 times a year and vote on dividend policies, who the CEO will be, etc.
They don't set lending criteria or select banking clients - that's for company staff like senior and middle managers. Lots of banks lent money to Japan and Germany - JP Morgan, Citibank (then National City), Chase, Chemical Bank, etc. How many connections can you chase down there?
Your line of reasoning would also mean that Ambassador Pamela Harriman (a Clinton appointee) was in bed with the Naziis, which isn't true, though she did spend a lot of time on her back, back in the day. If she slept with a Nazi it was likely by mistake - she liked her cocktails strong and her men rich, much like Teresa Heinz Kerry.
BMW built engines for the Messerschmidt warplane; the Volkswagen was commissioned by Hitler. Bayer made chemicals for the German military; the Fuhrer rode in a chauffered Mercedes - is Chrysler liable? Is my pharmacist complicit? How about your area BMW dealer - is he a Nazi? Should I destroy my Jetta?
And where the hell is my stolen Iraqi oil? I just had to spend $80 to fill up the Jetta, the Porsche, and the Touareg!! Damnit! I thought that's the only reason why fight terrorism - cheap oil!! (And to help our "Zionist allies" conquer the world, or something, again.)
BTW, if you're looking for Nazi connections, look no further than the Palestinians (viz, the Grand Mufti of Jerusalem) and the Egyptians, who used to be staunch allies of the Reich!!