What rank is immediately below Sergeant Major?

The rank that is immediately below Sergeant Major is Master Sergeant. This is a key distinction within military rank structures, particularly in the United States Army and Marine Corps. The Master Sergeant serves in a senior non-commissioned officer capacity, typically overseeing the operations and administration within units, providing leadership and guidance to junior enlisted soldiers.

In the context of the rank hierarchy, the Master Sergeant holds a vital role just beneath the Sergeant Major, which is predominantly a leadership position focused on advising commanders and leading larger groups. This close association in terms of responsibilities and seniority is what signifies the Master Sergeant's position right below the Sergeant Major, making it the correct answer.