Throughout an illustrious career that spanned the half-century from the Spanish-American War through World War II, Benjamin O. Davis proved that determination and diplomacy could overcome the barriers raised by racial bigotry. Today there are as many as 10,000 black officers in the army. In Davis's day there weren't more than two or three. As Marvin Fletcher's admiring but balanced portrait shows, this enormous change owes not a little to the...