Marine Corps doctrine is defined as which of the following?

• A. A teaching of the fundamental beliefs of the Marine Corps on the subject of war, from its nature and theory to the preparation and conduct
• B. A collection of tactics
• C. The legal code
• D. A field manual for training

Answer: (B)

Doctrine is the guiding framework that describes why and how Marines fight. It articulates the fundamental beliefs about war—the nature of war, the theory behind warfare, and the principles that determine how forces should prepare and conduct themselves. This makes doctrine broader than just a set of tactics; it provides the lens through which planning, training, organization, and execution are aligned to achieve objectives. It is not a legal code, nor merely a field manual with step-by-step instructions. Tactics are part of how you implement doctrine, but doctrine itself explains the why and the overarching approach that shapes all those actions.