Which rank is designated as O-4 in the Marine Corps?

In the Marine Corps, the rank designated as O-4 is Major. This rank is significant as it represents a level of leadership and responsibility in the military hierarchy. A Major typically commands a battalion and is often involved in strategic planning and operations.

The rank structure designates O-1 to O-10 levels, with O-4 specifically designating Major. Understanding military ranks is crucial for recognizing the roles and responsibilities associated with each position in the Marine Corps.