Military science itself is but the art of employing force to vindicate, or execute, authority. To meet an emergency adequately, wisely, and successfully, is the expressive logic of personal, municipal, and military action. The brain power is banded to various shaftings, and the mental processes may differ by virtue of different applications; but the prime activities are the same. In military studies, as in all collegiate or social preparation, the soldier, the lawyer, or the scientist, must be in the man, and not the necessary product of a certificate or a diploma. The simplest possible definition of a few terms in military use will elucidate the narrative as its events develop the War for American Independence, under the direction of Washington as Commander-in-Chief. Six cardinal principles are thus stated: I. STRATEGY.—To secure those combinations which will ensure the highest possible advantage in the employment of military force. NOTE.—The strategical principles which controlled the Revolutionary campaigns, as defined in Chapter X. had their correspondence in 1861–1865, when the Federal right zone, or belt of war, was beyond the Mississippi River, and the left zone between the Alleghany Mountains and the Atlantic Ocean. The Confederate forces, with base at Richmond, commanded an _interior line_ westward, so that the same troops could be alternatively used against the Federal right, left, and centre, while the latter must make a long détour to support its advance southward from the Ohio River. Federal superiority on sea and river largely contributed to success. American sea-control in 1898, so suddenly and completely secured, was practically omnipotent in the war with Spain. The navy, was a substantially equipped force at the start. The army, had largely to be created, when instantly needed, to meet the naval advance. Legislation also favored the navy by giving to the commander-in-chief the services of eminent retired veterans as an advisory board, while excluding military men of recent active duty from similar advisory and administrative service. II. GRAND TACTICS.—To handle that force in the field.