"To become the enemy, see yourself as the enemy of the enemy." Miyamoto Musashi, Japanese Samurai
Samurai code that warriors learn to be honest, fair, defend their lords & protect them, and even risk their lives and avenge their lords death. They learn to value loyalty, and even kill themselves to not accept defeat. This helped samurais with a code of conduct to follow. Bushido taught samurais discipline and honor. Without it, there would be no rules to follow, they could be scared of war, and they won't have a strong training system.