1-1. Every profession develops a unique body of knowledge. For the Army Profession, this body of professional knowledge is doctrine. United States (U.S.) Army doctrine is about the conduct of operations by Army forces in the field (and to a limited extent the guidelines for training for operations). Doctrine is the body of professional knowledge that guides how Soldiers perform tasks related to the Army’s role: the employment of landpower in a distinctly American context. Doctrine establishes the language of the profession. Just as physicians must remain proficient and current regarding the body of medical knowledge, Army professionals must remain proficient and current in doctrine. The lives of the men and women who make up the Army—not to mention the security of the Nation—rely on all leaders and Soldiers to be proficient in the Army’s body of professional knowledge: doctrine.