If you could choose only two things as a staple of any war movie, they'd probably be military jargon (like "roger" in military aviation) and hand signals. Whether it's Easy Company deep behind enemy ...

A not-insignificant part of driving a vehicle of any kind, no matter how many wheels it has, is knowing the necessary methods ...

Losing an arm cuts more than muscle and bone. It also severs the easy, wordless link between what you want to do and what your hand can actually do.