The celestial saint of Germany is St. Maurice, a pure African. While in command of a Roman legion in Switzerland in 287 A.D., he refused to attack the Christians when ordered by Emperor Maximian Herculius. For his defiance he was killed. His picture is in many German cathedrals and museums with the German eagle on his head.
Trajan ordered the commander of his Mauritanian auxiliaries, Lusius Quietus, to clean the suspects out of these regions(egypt). Quietus organized a force and killed many Cypriote, Mesopotamian and Syrian Jews - in effect wiping them out; as a reward, he was appointed governor of Judaea. (He is one of the few blacks known to have made a career in Roman service.) He was responsible for a forced policy of hellenization; in response, the rabbis ordered the Jewish fathers not to teach their sons Greek
It seems there were individual black soldiers serving rome,but i dont think there was hole units of black soldiers.
L