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
garrison of 25,000 men in his rear, and an Austrian force of 40,000
before him. But in 1806 the great superiority of his army enabled him to
detach forces to besiege the principal fortresses of Silesia, and still
to continue his operations with his principal forces. The chief of the
army may meet the enemy under circumstances such as to induce or compel
him to give battle. If he should be victorious, the enemy must be
pursued and harassed to the uttermost. If he should be defeated, he must
form the best plan, and provide the best means of retreat. If possible,
he must take shelter in some line of fortifications, and prepare to
resume the offensive. Lines of intrenchment and temporary works may
sometimes serve him as a sufficient protection. Finally, when the
unfavorable season compels him to suspend his operations, he will go
into winter cantonments, and prepare for a new campaign.

Such are the ordinary operations of war: its relations to strategy must
be evident, even to the most superficial reader.

Not unfrequently the results of a campaign depend more upon the