Complex sentence: He completed recruit training with the 3rd Recruit Training Battalion, Marine Corps Recruit Depot Parris Island, South Carolina; and advanced infantry combat training with Company M, 3rd Battalion, 1st Infantry Training Regiment, Camp Lejeune, North Carolina.
Split into simpler sentences: He completed recruit training with the 3rd Recruit Training Battalion, Marine Corps Recruit Depot Parris Island, South Carolina. He then went to advanced infantry combat training with Company M, 3rd Battalion, 1st Infantry Training Regiment, Camp Lejeune, North Carolina.