is that very few black troops were allowed in combat or given combat assignments.

It wasn't a totally white war, but it almost might as well have been.

Of course, when black troops were allowed to fight, they did quite well. The Tuskegee Airman are a prime example.

https://en.wikipedia.org/wiki/Tuskegee_Airmen

Also, looking at other minorities, the most decorated unit in the US Army was a regiment of Japanese-Americans who fought through much of the Italian campaign, the 442 Regimental Combat Team.

https://en.wikipedia.org/wiki/442nd_Infantry_Regiment_(United_States)

The armed services were finally integrated shortly after WWII by Pres Truman.