_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, which may deviate from his general line of operations. The ulterior events of the campaign may possibly cause him to make these new, or accidental lines, his lines of operations. The approach of hostile forces may cause him to detach secondary corps on secondary lines; or to divide his army, and pursue double or multiple lines. The primitive object may also be relinquished, and new ones proposed, with new lines and new plans of operations. As he advances far from his primitive base, he forms new depots and lines of magazines. He may encounter natural and artificial obstacles. To cross large rivers in the face of an enemy is a hazardous operation; and he requires all the art of the engineer in constructing bridges, and securing a safe passage for his army. If a fortified place is to be taken, he will detach a siege corps, and either continue his march with the main army, or take a strategic position to cover this siege. Thus Napoleon, in 1796, with an army of only 50,000 combatants, could not venture to penetrate into Austria, with Mantua and its