Complex sentence: The III Marine Expeditionary Force is a Marine Air-Ground Task Force of the United States Marine Corps that is forward-deployed and able to deploy rapidly and conduct operations across the spectrum from humanitarian assistance and disaster relief to amphibious assault and high intensity combat.
Split into simpler sentences: The III Marine Expeditionary Force (III MEF) is a formation of the Marine Air-Ground Task Force of the United States Marine Corps. It is forward-deployed and able to deploy rapidly and conduct operations across the spectrum from humanitarian assistance and disaster relief to amphibious assault and high-intensity combat.