Pretty much what it says on the tin; Roosevelt is President when the First World War breaks out in Europe. He gets us involved as early as he can - he really wanted to get involved there. Anyways that's all kinda background stuff assumed in the question which is: Could/would Teddy Roosevelt want to / be able to desegregate the United States military in any meaningful fashion during the First World War?
While it does seem unlikely, Roosevelt is intensely popular and has a very forceful personality. He also invited (IIRC) Booker T. Washington to the White House during his OTL term as President. Additionally if America gets involved in the war sooner they may (but probably won't) need the troop boost that desegregation would give them.
IF (big if there) this all happens and the war pans out more or less OTL (in that the Allies win; I'm not overly concerned with how or what happens in Europe at the moment) what would be the effect on race relations in the United States?
Part of racism is the devaluation of African Americans as lazy, barbaric, etc. but many WWII vets gained a great respect for their black fellow Americans based on shared service together in Europe. Might a similar effect be achieved here or was the white brain just not developed enough to comprehend the humanity of the African American?