Dynamic Campaign Generator (DCG) is a mod for the game "Men of War" and some of its successors that randomly generates skirmish missions and lets you keep your surviving forces from one battle to another. Some people find this mod tricky to install the first time - please read the readme.txt carefully and ask for help (if you need it) on our forums here on this site, or at the game developer's site.
U-Boote crews didn't really wear uniforms.
They did, however it was more common for them to not wear them during missions. But since the game doesnt include halfnaked, bearded U-Boot 3d humans, we cant give you them either (since none of us are able to do 3d humans and animate them).
~Zeke.