Complex sentence: His college days were cut short in 1951 when he was recalled to serve in the Korean War, first as an official Army war correspondent with the 223rd Infantry Regiment, then as public information officer for U.S. X Corps, which included the 1st Marine Division.
Split into simpler sentences: His college days were cut short in 1951 when he was recalled to serve in the Korean War. In Korea he first served as an official Army war correspondent with the 223rd Infantry Regiment, then as public information officer for U.S. X Corps, which included the 1st Marine Division.