system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 How did armored warriors avoid mistakenly fighting their own comrades during combat?

I am referring specifically to when there were no visible markings/insignia to indicate who was who.
gpt
This is exactly why heraldry existed.

In that age you wanted to have colors or obvious symbols on your armor and shield so that people would know if you were friend or foe.

Otherwise friendly fire was a real problem.