It's quite interesting that two biggest wars of the last century were started by Germany.

Stockpiling weapons works as a deterrent. Think about it, when you're a small guy at school you're asking for trouble. At some point some bully will see you as inferior and want to unload his frustration and anger on you, because it's safe for him. Guys who go to the gym and do sports have it much easier. Bullies just avoid them because even if they win they walk out of it with a broken nose or a black eye = not worth it.