maxim, however, must sometimes be disregarded by an army of undisciplined troops, in order to avoid entire destruction; but the total abandonment of a line of operations is always attended with great loss, and should be regarded as a mere choice of evils.  A regular army can always avoid this result, by changing the direction of its line; thus frequently gaining superior advantages in the new theatre of action.  If the plan of this change be the result of a good coup d’oeil, and it be skilfully executed, the rear of the operating army will be secure from the enemy; and moreover, he will be left in doubt respecting its weak points.  But such is the uncertainty of this manoeuvre, that it is very rarely taken by the best troops, unless actually forced upon them.  If the army be of incongruous materials, generally a change of direction will be less advantageous than to entirely abandon the line, and save as many as possible of the troops for some new plan of operations. (Maxim 20.) If, however, the undisciplined army be sustained by fortifications, it can take up the accidental line of operations in the same manner, and with the same probability of success, as is done by a regular force.

We have examples of accidental lines in the operations of the king of Prussia, after the battle of Hohenkirchen, and of Washington, in New-Jersey, after the action of Princeton.  This is one of the finest in military history.  Napoleon had projected a change in his line of operations, in case he lost the battle of Austerlitz; but victory rendered its execution unnecessary.  Again in 1814 he had planned an entire change of operations; but the want of co-operation of the forces under Mortier and Marmont forced him to abandon a plan which, if properly executed, had probably defeated the allies.  Jomini pronounced it one of the most brilliant of his military career.

Having explained the principal terms used in strategy, let us trace out the successive operations of war in their usual strategic relations.

We will suppose war to be declared, and the army to be just entering upon a campaign.  The political and military authorities of the state determine upon the nature of the war, and select the theatre of its enterprises.  The chief selects certain points, on or near the borders of the seat of war, where his troops are to be assembled, and his materiel collected.  These points, together, form his base of operations.  He now selects some point, within the theatre of the war, as the first object of his enterprises, and chooses the line of operations most advantageous for reaching this objective point.  The temporary positions taken on this line become strategic positions, and the line in his rear, a line of defence.  When he arrives in the vicinity of his first object, and the enemy begins to oppose his enterprises, he must force this enemy to retreat, either by an attack or by manoeuvres.  For this purpose he temporarily adopts certain lines of manoeuvre,