When an army moves at a distance from the enemy, the columns may be
disposed along the road so as to favor the artillery and baggage. But
when it is marching into action, the different corps must be formed in
close columns in order of battle. The generals must take care that the
heads of the columns, which are to attack together, do not outstep each
other, and that in approaching the field of action they preserve the
relative intervals required for deployment.
“The marches that are made preparatory to a battle require,” says
Frederick, “the greatest precaution.” With this view, he recommends
his generals to be particularly on their guard, and to reconnoitre
the ground at successive distances, in order to secure the initiative
by occupying those positions most calculated to favor an attack. On
a retreat, it is the opinion of many generals that an army should
concentrate its forces, and march in close columns if it is still
strong enough to resume the offensive; for by this means it is easy
to form the line when a favorable opportunity presents itself, either
for holding the enemy in check or for attacking him if he is not in a
situation to accept battle.
Such was Moreau’s retreat after the passage of the Adda by the
Austro-Russian army. The French general, after having covered the
evacuation of Milan, took up a position between the Po and the Tanaro.
His camp rested upon Alexandria and Valentia, two capital fortresses,
and had the advantage of covering the roads to Turin and Savona, by
which he could effect his retreat in case he was unable to accomplish a
junction with the _corps d’armee_ of Macdonald, who had been ordered to
quit the kingdom of Naples, and hasten his march into Tuscany.
Forced to abandon his position in consequence of the insurrection in
Piedmont and Tuscany, Moreau retired upon Asti, where he learned that
his communication with the river of Genoa had just been cut off by the
capture of Ceva. After several ineffectual attempts to retake this
place, he saw that his only safety depended upon throwing himself into
the mountains.
To effect this object, he directed the whole of his battering train
and heavy baggage by the Col de Fenestrelle upon France; then opening
himself a way over the St. Bernard, he gained Loano with his light
artillery and the small proportion of field equipment he had been able
to preserve.
By this skilful movement, he not only retained his communications with
France, but was enabled to observe the motions of the army from Naples,
and to facilitate his junction with it by directing the whole of his
force upon the points necessary for that purpose.
Macdonald, in the meantime, whose only chance of success depended on
concentrating his little army, neglected this precaution, and was
beaten in three successive actions at the Trebia.
By this retardment of his march, he rendered all Moreau’s measures to
unite the two armies in the plains of the Po useless, and his retreat,
after his brilliant but fruitless efforts at the Trebia, defeated the
other arrangements, also, which the former had made to come to his
support. The inactivity of Marshal Suwarrow, however, finally enabled
the French general to accomplish his junction with the remains of the
army from Naples. Moreau then concentrated his whole force upon the
Appenines, and placed himself in a situation to defend the important
positions of Liguria, until the chances of war should afford him an
opportunity of resuming the offensive.
When, after a decisive battle, an army has lost its artillery and
equipments, and is consequently no longer in a state to assume the
offensive, or even to arrest the pursuit of the enemy, it would
seem most desirable to divide what remains into several corps, and
order them to march by separate and distant routes upon the base of
operation, and throw themselves into the fortresses. This is the only
means of safety: for the enemy, uncertain as to the precise direction
taken by the vanquished army, is ignorant in the first instance which
corps to pursue, and it is in this moment of indecision that a march is
gained upon him. Besides, the movements of a small body being so much
easier than those of a larger one, these separate lines of march are
all in favor of a retreating army.