Frederick observes, that “the passage of great rivers in the presence
of the enemy is one of the most delicate operations in war.” Success on
these occasions depends on secrecy, on the rapidity of the manœuvres,
and the punctual execution of the orders given for the movements of
each division. To pass such an obstacle in presence of an enemy, and
without his knowledge, it is necessary not only that the previous
dispositions should be well conceived, but that they should be executed
without confusion.
In the campaign of 1705, Prince Eugene, of Savoy, wishing to come to
the assistance of the Prince of Piedmont, sought for a favorable point
at which to force the passage of the Adda, defended at that time by
the French army, under the command of the Duke de Vendome.
After having selected an advantageous situation, Prince Eugene erected
a battery of twenty pieces of cannon on a position which commanded the
entire of the opposite bank, and covered his infantry by a line of
entrenched parallels constructed on the slope of the declivity.
They were working vigorously at the bridge, when the Duke de Vendome
appeared with his whole army. At first he seemed determined to oppose
its construction, but after having examined the position of Prince
Eugene, he judged this to be impracticable.
He therefore placed his army out of reach of the prince’s batteries,
resting both his wings upon the river, so as to form a bow, of which
the Adda was the cord. He then covered himself with entrenchments and
abattis, and was thus enabled to charge the enemy’s columns whenever
they debouched from the bridge, and to beat them in detail.
Eugene, having reconnoitred the position of the French, considered the
passage impossible. He therefore withdrew the bridge, and broke up his
camp during the night.
It was by this manœuvre, also, that, in the campaign of 1809, the
Archduke Charles compelled the French to reoccupy the isle of Lobau,
after having debouched on the left bank of the Danube. The march of the
Archduke Charles was wholly concentric. He menaced Grosaspern with his
right, Esling with his centre, and Enzersdorf with his left.
His army, with both wings resting on the Danube, formed a semicircle
around Esling. Napoleon immediately attacked and broke the centre of
the Austrians; but after having forced their first line, he found
himself arrested by the reserves. In the meantime, the bridges upon
the Danube had been destroyed, and several of his corps, with their
parks of artillery, were still on the right bank. This disappointment,
joined to the favorable position of the Austrians, decided Napoleon
to re-enter the isle of Lobau, where he had previously constructed a
line of field-works, so as to give it all the advantages of a well
entrenched camp.