I'd say there is no tolerated outward signs of racism in the Army that I ever sensed. My husband never expresses racist attitudes at all. Back then, he always bought tickets to black history month events and the ball and stuff like that because some of our friends were black. A gf of mine, a black woman, told me she felt prejudice from time-to-time though. It's a tough state-of-mind and condition to overcome from both sides, depending on one's upbringing imo.
As far as soldiers go, you're right that they rely on each other to have the other's back so it behooves everybody to be friends! I needed a break when my husband retired but, I must say, I miss Army life now. Life was never dull but could be very stressful at times.
My husband was attached to the Pentagon on 9/11 so we could have had personal tragedy that day. I knew he had headed to Fort Belvoir though as I was watching my TV and saw the towers fall down and later the Pentagon being attacked, etc. It was my parent's anniversary so I was on the phone with them wishing them a happy day when that occurred. I'll never forget that moment. We hung up and I fell to my knees and began to pray as I lived 10 miles from the Pentagon at the time. Who knew what was going to happen next?