What is the rank of a Marine Corps officer just below a Captain?

The rank of a Marine Corps officer just below a Captain is 1st Lieutenant. In the United States Marine Corps, the rank structure progresses in a specific order, and officers typically advance through ranks that reflect their experience and responsibilities.

A Captain is ranked above a 1st Lieutenant, making the latter the correct answer in this context. The rank of 1st Lieutenant serves as a transitional stage, where officers may take on additional leadership roles and responsibilities while preparing for the level of command associated with the Captain rank.

Understanding the hierarchy is crucial for recognizing the roles and responsibilities that different ranks entail within the Marine Corps. This knowledge is essential for effective communication and collaboration among ranks in military operations.