IF the muse were mine to tempt it
And my feeble voice were strong,
If my tongue were trained to measures,
I would sing a stirring song.
I would sing a song heroic
Of those noble sons of Ham,
Of the gallant colored soldiers
Who fought for Uncle Sam!
In the early days you scorned them,
And with many a flip and flout
Said 'These battles are the white man's,
And the whites will fight them out.'
Up the hills you fought and faltered,
The term  “A white man’s war”  represented several public feelings and beliefs about black people in war stating that they were inferior and not suited to fight alongside white men. 
 The “flip and flout” refers to the opinions of naysayers concerning whether black people could participate.
The Colored Soldiers