Complex sentence: He was promoted to colonel in March 1863 and again to brigadier general of volunteers in May of the same year, and commanded the southern defenses of Washington, D.C. until the end of the war.
Split into simpler sentences: He was promoted to colonel in March 1863 and again to brigadier general of volunteers in May of the same year. He commanded the southern defenses of Washington, D.C. until the end of the war.