What is the second highest officer rank in the Marine Corps?

The second highest officer rank in the Marine Corps is indeed Lieutenant Colonel. This rank comes after Colonel, which is the highest field grade officer rank before reaching the general officer ranks. In the structure of Marine Corps ranks, the progression from Major to Lieutenant Colonel signifies a significant advancement in responsibility and leadership. A Lieutenant Colonel typically serves as a battalion commander and plays a crucial role in planning and executing missions, overseeing training, and managing personnel.

In contrast, the other ranks listed—such as Major, which is below Lieutenant Colonel, and Colonel, which is above it, or Brigadier General, which is the lowest of the general officer ranks—do not fit the criteria of being the second highest rank. Thus, understanding the rank structure within the Marine Corps helps clarify why Lieutenant Colonel holds its established position as the second highest rank within the officer category.