“Ideas matter.” So says the first sentence in the Army’s newly published Capstone Concept, titled Operational Adaptability: Operating Under Conditions of Uncertainty and Complexity in an Era of Persistent Conflict. It bears the imprimatur of its primary author, Brig. Gen. H.R. McMaster, a revolutionary thinker. Not surprisingly then, its the most revolutionary document the Army has produced in a long time because it discards two very big ideas – actually it discards one and demolishes the other — that have driven Army doctrine and weapons buying over the past three decades. The first idea retired by the new capstone concept...