 Complete the following phrase:  In June he returned to Boston and enrolled in Harvard Law School, but by September 1862 became a first lieutet in the 44th Massachusetts regiment. When the United States Colored Troops USCT were formed for African-American recruits, he was promoted to captain on March 31, 1863, of the 54th Massachusetts. However, the number of volunteers was higher than expected, so he was promoted to lieutet colonel, and helped organize the 55th Regiment Massachusetts Volunteer Infantry under command of Norwood Penrose Hallowell. The 54ths role in the 