STRATEGY (OF. strategic, Fr. straWgie, from Gk. arparuyia, stratgia, generalship, from crparu6c, strategos, general, from stra tos, army, encampment, from aropevviTat, storen nynai, hat. sternere, Skt. star, to spread, extend, strew + WyEtv,agein, to lead). Strategy is one of the two great subdivisions of the art of war, and comprises all those larger measures which relate to the grand field of operations, the object of which is to have the troops enter the contest. of arms, the battle, under the most favor able conditions, involving the direction of the troops toward the battlefield, as well as the measures taken to reap the rewards of success. It has been defined as the use of battles in war, in contradistinction to tactics (the other great subdivision of the art of war), which is the use of troops in battle; or, again, as the art of lead ing armies, while tactics is the art of leading the smaller subdivisions of armies and is fully treated under its own head. See TACTICS.
The scope of strategy has been greatly extended with time. Formerly, it did not enter as 'a fac tor in war until the armies were actually in the field; but to-day national policy is also a de termining factor, and one of vast importance. in view of the fact that modern wars are conducted on a grand scale and with great rapidity, there fore requiring definite plans to he prepared be forehand, in which questions of statesmanship and diplomacy are necessarily leading factors. Moreover, finance and commerce must also be considered.
Among the principles upon which strategy is based or according to which it is directed are: ) National policy and strategy must be kept in perfect agreement in war, and closely allied at every point, to accomplish the best re sults.
(2) When countries are at war each will prob ably finally concentrate its troops in a single army, so as to be able to strike decisive blows with its united power; hence the principal ob jective, against which all efforts should he di rected at the outset, is the enemy's main army.
(3) Every effort must be made to bring to gether at the decisive moment all available forces.
These relate to the general objects of the war, the theatre of operations, and the entire field army as a whole. Separate actions may take place in various parts of the theatre, and they, too, will involve strategic principles, similar in character. but of minor importance.
(4) The offensive alone promises decisive re sults.
(5) The defensive can only avoid defeat; it cannot win victory.
(6) It is impossible to be too strong for a decisive battle.
(7) Concentration of the forces is a necessary condition for decisive action.
(8) No alteration in the plan of operations should be made after the campaign has definitely opened, unless enforced by the enemy or by the elements or unforeseen circumstances.
During the progress of military events certain of the latter will generally have a common ob ject, and will be closely related in other respects. Every such group of events, composed in general of marches, positions, and battles, is designated an operation. A group of closely related opera tions constitutes a campaign. To-day the opera tions of a campaigm are practically continuous, but, in order to be so, there must be a base of supplies. where ammunition, food, forage, and so on are accumulated for the support and main tenance of the army in its advance. Formerly this base was .fixed, and could he fortified and stocked with supplies beforehand, but modern war demands a movable base, usually a network of railroads, but sometimes furnished by a fleet.
The lines along which the army advances from its base toward its objective are called lines of oporittion, and those by which the army obtains its subsistence and supplies, lines of communi cation. The base, the lines of operation, and the lines of communication, being of vital importance to the operating army, are naturally the objects of the enemy's attacks and usommVIes.