Complex sentence: He served in the U.S. Army Corps of Engineers from 1943 to 1946 where he attained the rank of sergeant and then graduated from Howard University where he received his B.A. in 1947.
Split into simpler sentences: He served in the U.S. Army Corps of Engineers from 1943 to 1946 where he attained the rank of sergeant. After the war he graduated from Howard University where he received his B.A. in 1947.