Write about the various aspects of leadership.  Tie those aspects into the military and the United States Marine Corps concept of leadership (i.e. Leadership traits, leadership principles).  Speak about the importance of the NCO rank (Corporal and Sergeant) and how their leadership leads to a more professional and efficient military.  Here is a video that gives a brief synopsis on those two ranks:  https://www.youtube.com/watch?v=4gNuuloKom8