Quick CTF Question

What’s the origin of Capture the Flag in shooting games? It’s been in every FPS I’ve ever played, from Quake to Halo.
And on a related note, what’s the origin of the ideal of “Red vs. Blue” (not the series, the ideal)?
I know both of those might seem like stupid questions but I’m just a bit curious…
(On a related note, did anyone notice in Halo CE and Halo 2 that the different colors had different animals? Cobras for the Red team and Hawks for the Blue? What happened to that?)

I really don’t understand why it would be Red vs Blue. Why not Red vs Green? Or Blue vs Orange? Purple vs Yellow?

red and blue are two primary colors, I think yellow was not used because… it’s yellow

CTF is also in paintball

Actually red and blue are the perfect colors - they contrast each other in their symbolism as well as their look. Red symbolizes stronger emotions whilst blue symbolizes more passive emotions. No other color combination would have been better.

Sounds plausible - any other colors would sort of be gaudy. Unless you had Yellow vs Purple for Elite Team matches (Heretics vs. Loyalists)
Thanks for the feedback, it was just a question that was nagging me. I always thought about what it would be like if they had symbols instead of colors - Circle vs Square or something. That way people could keep their respective colors but they’d have their team symbol emblazoned on them (Chest, Helmet, Back, Shoulders, etc.)
I remember a Quake gametype having something like that.