e preferred the certainty of a partial success to the risk
attending a victory which would have been a decisive one. In the same
campaign Napoleon's passage of the Po is another example of the high
strategic importance of the choice of the point of crossing. The army of
the reserve, after the engagement of the Chiusella, could either march
by the left bank of the Po to Turin, or cross the river at Crescentino
and march directly to Genoa. Napoleon preferred to cross the Ticino,
enter Milan, effect a junction with Moncey who was approaching with
twenty thousand men by the Saint-Gothard pass, then to cross the Po at
Piacenza, expecting to get before Melas more certainly in that direction
than if he came down too soon upon his line of retreat. The passage of
the Danube at Donauwerth and Ingolstadt in 1805 was a very similar
operation. The direction chosen for the passage was the prime cause of
the destruction of Mack's army.

The proper strategic point of passage is easily determined by
recollecting the principles laid down in Article XIX.; and it is here
only necessary to remind the reader that in crossing a river, as in
every other operation, there are permanent or geographical decisive
points, and others which are relative or eventual, depending on the
distribution of the hostile forces.

If the point selected combines strategic advantages with the tactical,
no other point can be better; but if the locality presents obstacles
exceedingly difficult to pass, another must be chosen, and in making the
new selection care should be taken to have the direction of the movement
as nearly as possible coincident with the true strategic direction.
Independently of the general combinations, which exercise a great
influence in fixing the point of passage, there is still another
consideration, connected with the locality itself. The best position is
that where the army after crossing can take its front of operations and
line of battle perpendicular to the river, at least for the first
marches, without being forced to separate into several corps moving upon
different lines. This advantage will also save it the danger of fighting
a battle with a river in rear, as happened to Napoleon at Essling.

Enough has been said with reference to the strategical considerations
influencing the selection of the point of crossing a river. We will now
proceed to speak of the passage itself. History is the best school in
which to study the measures lik