Complex sentence: The 2nd Marine Expeditionary Brigade is a unit in the II Marine Expeditionary Force (II MEF) and "middleweight" crises response force of choice in the European and Southern Command Areas of Operation.
Split into simpler sentences: The 2nd Marine Expeditionary Brigade is a formation of the II Marine Expeditionary Force (II MEF). It advertises itself as a "middleweight" crises response force of choice in the European and Southern Command Areas of Operation.