In addition to the perils of war faced by all Civil War soldiers, black soldiers faced additional problems stemming from racial prejudice. Racial discrimination was prevalent even in the North, and discriminatory practices permeated the U.S. military which caused the problem in particular.
The reason why Japanese Emperor Hirohito authorize his military to bomb Pearl Harbor in the late 1941 was because he has hopes in destroying the U.S navy that is residing in Pearl Harbor.