comrade; a friend, especially someone you have fought together with in a war or worked with

comrade in arms; a friend who fought in a war or experienced a difficult or dangerous situation with you

It doesn't really matter though, I like the second word more. It was one of the greatest tv shows I've watched. The story was really deep and made me think a lot of things about a war, life and the comrade in arms. Plus, the actors and actress' performance were awesome too. There should be no war all over the world and the comrade in arms should be remembered forever.