Note: Originally, you had to be Jewish to become Christian. https://en.m.wikipedia.org/wiki/Jewish_Christian Attila would be possible. Otherwise the chronology would be too far off.
You first need to provide the scope of what he has access to 1) The entire german nation with its preWW2 technology and industry 2) Only german industries without the tanks, planes and his subordinates 3) Only his subordinates (loyal or not) 4) Only himself and the tanks, planes and his technology (including rockets) Depending on the scope of what he has, it can have some very different outcomes. For example, if he only has himself and his technology, he will be nothing more than a glass cannon, because he will only be able to use them once or twice and he has to throw them away afterwards. Modern shell propellant is not the same as black powder, and they didn't even have black powder in the 1st century.
That was during the revolution, not the civil war era. Nope, if you want to go down this rabbit hole a bit... What you have is this is only a part of changing the perception of the average American. Example: Americans back in the 40s and 50s are being called facists and nazi's , just like how the media calls trump supporters... but... they are the ones that fought against and help defeat the nazi... Were bigger supporters of freedom, the constitution, less Government etc... than now. They were less like the nazi then people of today. Our history, perception, and this is not the only example, is heavily being skewed by Media/Entertainment/Colleges/State School boards/Tech Industry... All heavily controlled by those aligning themselves towards 1 political party. Just use wisdom and delve a bit deeper than surface level info to arrive at your conclusions.
Hitler was charismatic guy, find another guy with charisma and weird ambitions hmm Trump? Mexican wall xd