by which supplies
reached the enemy--they could not maintain over the entire district the
watchfulness necessary wholly to intercept communication between the two
shores. Neither could they for the briefest period abandon their station
at the river's mouth, without affording an opportunity to the enemy; who
was rendered vigilant by urgent necessities which forced him to seize
every opening for the passage of stores. From the repulse of five out of
the seven ships detailed for the control of the river, it resulted that
the enemy's communications, on a line absolutely vital to him, and
consequently of supreme strategic importance, were impeded only, not
broken off. It becomes, therefore, of interest to inquire whether this
failure can be attributed to any oversight or mistake in the
arrangements made for forcing the passage--in the tactical dispositions,
to use the technical phrase. In this, as in every case, those
dispositions should be conformed to the object to be attained and to the
obstacles which must be overcome.

The purpose which the admiral had in view was clearly stated in the
general order issued to his captains: "The captains will bear in mind
that the object is _to run the batteries at the least possible damage to
our ships_, and thereby secure an efficient force above, for the purpose
of rendering such assistance as may be required of us to the army at
Vicksburg, or, if not required there, to our army at Baton Rouge." Such
was the object, and the obstacles to its accomplishment were twofold,
viz., those arising from the difficulties of the navigation, and those
due to the preparations of the enemy. To overcome them, it was necessary
to provide a sufficient force, and to dispose that force in the manner
best calculated to insure the passage, as well as to entail the least
exposure. Exposure is measured by three principal elements--the size and
character of the target offered, the length of time under fire, and the
power of the enemy's guns; and the last, again, depends not merely upon
the number and size of the guns, but also upon the fire with which they
are met. In this same general order Farragut enunciated, in terse and
vigorous terms, a leading principle in warfare, which there is now a
tendency to undervalue, in the struggle to multiply gun-shields and
other defensive contrivances. It is with no wish to disparage defensive
preparations, nor to ignore that ships must be able to bear as well as
to give h