Baron de Jomini
The art of war, as generally considered, consists of five purely military branches-viz: strategy, grand tactics, logistics, engineering and tactics. A sixth and essential branch, hitherto unrecognized, might be termed Diplomacy in its Relation to War. Although this branch is more naturally and intimately connected with the profession of a statesman than with that of a soldier, it cannot be denied that if it be useless to a subordinate general it is indispensable ...