Lest we think Hitler was not a bigot, let's remember that Hitler publicly and loudly espoused Aryan supremacy (a myth which Jesse Owens punctured in the 1936 Olympics) and as dictator of Germany, conducted a systematic genocide which murdered six million Jews in a handful of years during WW II, which itself killed 50 million humans.  These indisputable facts are not "implacable WW II propaganda" like the notion of an Aryan "Master Race" most certainly was.  And,  despite FDR's alleged snub of Owens, Roosevelt's leadership of the US out of the Great Depression hugely benefitted African-Americans both socially and economically, as a reviving industrial boom fueled a migration of sharecropper families (including Jesse Owens' family) from the Jim Crow South to the relative freedom and prosperity of Northern industrial cities.

FDR died in 1945.  Three years later Harry Truman, another Democrat, ordered the racial integration of US armed forces with executive order 9981.