This power depends mainly on suddenness and mobility, and these qualities are most highly developed in combined expeditions.
_Diversions_ must be carefully distinguished from _eccentric attacks. Eccentric attacks_ are true offensive movements. They have a positive object, _i.e._, they aim to acquire something from the enemy; whereas diversions have a negative object, _i.e._, they aim at preventing the enemy doing or acquiring something. Eccentric attacks are usually made in greater force than diversions.
Examples.--Diversion.--Our raid on Washington in 1815. Landing force, about 4,000 men. Object, according to official instruction, "a diversion on the coasts of United States of America in favour of the army employed in the defence of Canada"; _i.e._, the intention was negative--preventive--defensive. _Eccentric Attack._--Operations against New Orleans in 1815. Intended force, 15,000 to 20,000 men. Object, "to obtain command of the embouchure of the Mississippi, and, secondly, to occupy some important and valuable possession, by the restoration of which the conditions of peace might be improved, &c."; _i.e._, the intention was positive--to acquire. Compare Rochefort Expedition (diversion) with those against Martinique and Belleisle (eccentric attacks) in the Seven Years' War.
This distinction gives a threefold classification of combined expeditions, as used by Elizabethan strategists, viz., raids, incursions, and invasions. These correspond respectively with our modern diversions, eccentric attacks, and true direct offensive.
From the nature of the ulterior object we get an important classification of wars, according to whether such object is _limited_ or _unlimited_.
(1) _War with limited object_ ("limited war") is where the object is merely to take from the enemy some particular part of his possessions or interests; _e.g._, Spanish-American War, where the object was the liberation of Cuba.
(2) _War with an unlimited object_ is where the object is to overthrow the enemy completely, so that to save himself from destruction he must agree to do our will (become subservient); _e.g._, Franco-German War.
Having determined the nature of the war by the nature of its object (_i.e._, whether it is offensive or defensive and whether it is limited or unlimited), Strategy has to decide on the system of operations or "plan of the war."