The UK has had its own issues with race/racism, not just with the highly visible Ethnic Minorities, such as Africans, Asians, but as a Welshman, my fellow Celts, have also faced discrimination, though, like the US, things are much better now, but in modern history, our racial problems have never been anywhere near as extreme as in the US, so it remains truly shocking to most Brits, to watch a WW2 film or TV show, and see black servicemen, fighting for a Nation that has not only never given them a single thing, but only ever taken off them, being treated so poorly. My Mamgu was as I said, in the Royal Artillery, and she spent a few months on ack ack guns in the City of Hull, in Yorkshire's East Riding, and, one morning going to get breakfast at a cafe, she and her friends witnessed the aftermath of a Lynching during the night, white GI's went crazy in some bar, and hung several Black GI's from lamposts in the street. That was one of the things she used to get nightmares about, the first time she told me, she was in tears, and, she was a tough old chick who used to blow Nazi planes out of the sky, so I very rarely ever saw her cry.
In WW2, were US Generals and politicians genuinely of the belief that Black/Ethnic American's were incapable of being soldiers, and would run away etc?
I know there were plenty of damned fools in the British Officer Corps, with exactly the same sort of stupid beliefs, but regardless of them, The British Army had, and had had for something well over 100 years+ Regiments raised and recruited throughout the Empire, not just the Crown Dominions (Canada, Australia, New Zealand, South Africa & technically Eire, until the Republic was formally established in 1949) but the Colonies and "possessions" too, such as India, Burma, the West Indies islands etc.
When you start examining the inscriptions listing the WW1 dead on the walls of the Menin Gate in Ieper, the Regiment names soon start jumping out, and always surprised the kids I was with as the British Schools History Curriculum didn't exactly have much in it really. The Kingston Rifles, the Bengali Lancers, the Ghurkas etc, etc.