Did ever soldier wear colors? In tv and movies both sides in a battle often wear similar armor and I'm often left wondering how people knew who was on their side and who wasnt once the line was broken.
The main factor to consider is that armies never fought in wild cluster****s, like you see in movies, but they rather fought in formations, so basically they knew that the guys in front of them were the enemy. There were also banners for every entourage of men, and some people (mostly knights, but some times also their men), wore their distinctive colours.
It's also important to distinguish periods here: in the 13th and 12th centuries, surcoats (painted with distinctive colours and patterns) were widely in use, while in the 15th century they were very infrequent. There is also the fact that many people within an army that fight in close distance know each other.
hi! you can get started with this post from the FAQ section Identifying sides in battle, and avoidance/frequency of "friendly fire"
Especially [/u/vonstroheims_monocle 's response] (https://www.reddit.com/r/AskHistorians/comments/1ub8vu/how_would_medieval_fighterswarriorsmilitary/cegjrut) in that thread might help.