A fault in tactics may occasion the loss of strategic lines; the best combined manoeuvres on the field of battle may lead to no decisive results, when the position, or the direction of the operation is not strategic; sometimes not only battles, but entire campaigns, are lost through neglect of the engineer's art, or faults in his dispositions; again, armies would be of little use without the requisite means of locomotion and of subsistence.
1.

_Strategy_ regards the theatre of war, rather than the field of battle.

It selects the important points in this theatre, and the lines of communication by which they may be reached; it forms the plan and arranges the general operations of a campaign; but it leaves it to the engineers to overcome material obstacles and to erect new ones; it leaves to logistics the means of supporting armies and of moving them on the chosen lines; and to tactics, the particular dispositions for battle, when the armies have reached the destined points.

It is well to keep in mind these distinctions, which may be rendered still more obvious by a few illustrations.

The point where several lines of communications either intersect or meet, and the centre of an arc which is occupied by the enemy, are strategic points; but tactics would reject a position equally accessible on all sides, especially with its flanks exposed to attack.