Complex sentence: In 1951 the 4th Marines were reactivated carrying the honor and lineage of both the old and new 4th Regiments, and later served in The Vietnam War as part of the 3rd Marine Division, under theIII Marine Amphibious Force from 1965 to 1969.
Split into simpler sentences: In 1951 the 4th Marines were reactivated carrying the honor and lineage of both the old and new 4th Regiments. The 4th Marines later served in The Vietnam War as part of the 3rd Marine Division, under theIII Marine Amphibious Force from 1965 to 1969.