Complex sentence: Boren served in the Oklahoma Army National Guard from 1963 to 1974, attaining the rank of Captain and serving as commander of the 2120th Supply & Service Company in Wewoka.
Split into simpler sentences: Boren served in the Oklahoma Army National Guard from 1963 to 1974. He attained the rank of Captain and served as commander of the 2120th Supply & Service Company in Wewoka.