The French Bridging Operations across the Danube in 1809

Austrian Pontoons or Military Bateaux

The French Bridging Operations across the Danube in 1809: The First Attempt: May 1809

The source of this document is: Douglas, Howard. An Essay on the Principles and Construction of Military Bridges and the Passage of Rivers in Military Operations 2nd edition; London : Thomas and William Boone; 1832. Pages 183 - 191

Napoleon's first passage of the Danubel in 1809, ought not to have succeeded.

The operations of that celebrated campaign are so instructive in all that relates to the important and difficult enterprise of passing a river, in face of an enemy, that, having treated of most of the constructions used on that occasion, it will be proper to introduce, here, a detailed account of the operation, and of the stupendous means and exertions used in carrying it into effect.

The victories of Eckmuhl and Ebersberg having operned the way to Vienna to the French army, the Archduke Charles, having passed the Danube at Ratisbon, advanced by the left bank of that river to endeavour to succour the capital: but upon hearing of the fall of that city, which surrendered on the 12th of May, he assembled his army, 75,000 strong, near the Bisamberg, a mountain close to the Danube, opposite to Kloster-Neuberg, and about three leagues above Vienna.

As soon as Vienna had fallen, Napoleon resolved to attempt the passage of the Danube, and to attack the army of the Archduke. This project was undertaken with characteristic promptitude and vigour. -- The very day that Vienna surrendered, the attempt was maed near Nussdorf, a town on the right bank of the river, about a league above the city. The ground on the left bank appeared to be extremely favorable for the offensive operations of the Frenc army, and the island opposite to Nussdorf offered considerable facilities for effecting a passage. It was, therefore, dtermined to endeavour to seize and secure that position, before the Austrians should have time to occupy it. A landing was promptly effected on the island with about 1000 men; but before they could be supported, they were attacked by superior numbers, and after a gallant resistance forced to yield.

The unsuccessful issue of this enterprise having obliged Napoleon to alter his plan, he determined to make his next attempt near Ebersdorf, about a league and a half below Vienna, where the river is divided, by two islands, into three branches. The channel nearest the right bank, (Plate 6), is about 430 yards wide. The main, or middle channel, which is only about 273 yards wide, lies between the island A, (Plate 6), and the Lobau. The island Lobau is about 4372 yards across, from N.E. to S.W., and about 2240 yards from N.W. to S.E., convexing, towards Entzersdorf and Essling, in a large, regular curve, round which the left branch of the river flows, in a widt of about 141 yards. This northerly branch is divided into several small channels, by the islands 10, 11, 12, etc. (Plate 6). Nearly opposite to the centre of a line drawn throught he villages of Essling, (Plate 6), and Gros Aspern, (which lies out of the plate about three quarters of a mile,) the river forms a deep, re-entering sinuosity, B C D, extremely favourable for effecting the passage of that branch of the river, and for the construction of a tete-de-pont.

The pontoneers having procured, at Vienna, materials sufficient for the construction of two bridges of boats, the island of Lobau, which the Austrians had but feebly occupied, was taken possession of, on the 18th of May, without much difficulty, by some troops of General Molitor's division, which were transported in row-boats. As soon as they made good their landing, the construction of two bridges of boats (1, 1X Plate 6)) was commenced. The bridge, 1, across the second branch, was formed of Austrian military bateaux: it was commenced at five o'clock in the morning. That across the first branch, 1, was formed of boats of the country, found at Vienna: itwas commenced early on the 19th, and on that day both were finished in time for the whole army to effect it's passage into the Lobau. The construction of a bridge of boats across the third branch, at C, (Plate 6), was commenced in the night of the 19th: for this, fifteen Austrian bateaux were used: -- it was finished in three hours; -- and before day-light on the 20th, three divisions of infantry, and some light cavalry, amounting in all to about 50,000 men, had crossed to the left bank of the Danube, and took position in the plain opposite to Gros Aspern and Essling.

Austrian Pontoons or Military Bateaux

The Archduke, with a part of his advanced guand, immediately reconnoitred the French army; and his cavalry gained some advantages over Napoleon's advanced corps, which, late in the evening, debouched from th low grounds near the river. The Archduke's plan was, not to dispute the passage of the river, but to attack the French army on the following day. With this intention he retired to Anderklau, (about four miles out of the plan,) leaving orders for the advanced corps to fall back, in proportion as the French should advance, and extend their line: -- Napoleon was thus permitted to occupy and establish himself, without resistance, in the villages of Gros Aspern and Essling, and to place his army, in position, between those important posts.

On the morning of the 21st, before the battle of that day commenced, the bridge of boats across the main, or middle channel of the river, was broken by a large vessel which the Austrians sent down the stream for that purpose; but the injury was speedily repaired, and the communication restored, by the activity of the pontoneers placed on duty there.

Towards evening (about 5 o'clock) the Archduke Charles commenced an attack on the French army; and throughout the remainder of that, and all the following day, a furious battle raged. The village of Essling was taken and retaken five times in the course of the 21st; and on the 22d, that village, and Gross Aspern likewise, became the scenes of repeated and sanguinary operations, with alternate success and discomfiture.

During the battle, the Austrians sent down the river, floating bodies of various descriptions, for the purpose of breaking the bridges; and notwithstanding the exertions of the pontoneers and boatmen, placed in surveillance above, both the bridges of boats, 1, 1X, (Plate 6) communicating with the Lobau, werecarried away. The French army was thus placed, for a considerable time, in the greatest of peril. A consciousness of this, so excited the exertions of the pontoneers, that, in the course of the afternoon, both bridges were repaired: but, late in the day, the bridge, 1, (Plate 6) across the first branch was again broken; and from want of materials could not speedily be made good.

If the Archduke Charles had employed the distinguished valour of his toops in preventing the French form issuing from the tete-de-pont, E, (Plate 6); and in defending the villages of Gros Aspern and Essling, which in the actions of the two following days, it cost him so much blood to recover, Napoleon's attempt to establish himself on the left bank of the river, would, in all probability, have been frustrated, without bringing on, and fighting, a general action, which Napoleon so much desired, and which the Austrians, since the surrender of Vienna, had no good motive for hazarding. It was perhaps possible to prevent the French from making a lodgment ont he left bank of the Danube, at a sinuosity so favourable, and under cover of the powerful batteries which had been established in the Lobau; nor would it have been pruden, ont he part of the Archduke, to expose his troops to their fire, by taking position close to the river, for the purpose of preventing the French from avancing into the plain. But village, 1000 yards distant -- military points -- upon the possession of which, obviously, the fate of the battle about to be fought must turn -- so far from being abandoned, should have been strongly occupied, entrenched, and defended to the last extremity: -- the severe losses sustained in recovering those villages, were tremendous sacrifices of much gallant blood, shed to retrieve the fatal error of not having secured positions so essential as these were found to be, to the Archduke's operations.

If the Austrians had attacked the French army early on the 20th, and had combined with the assault such an attempt to destroy the bridges, as that which proved successful on the 21st and 22d, the passage of the river could not have been effected; and the Austrian army would have been in a condition to follow up its success, instead of being so weakened by the subsequent victory, as to be forced to remain inactive, whilst Napoleon was preparing for a more formidable operation.

From the time that the bridge, 1, (Plate 6) on the first branch of the river was broken, on the morning of the 22d, the French army remained till night without communication with the right bank; and towards the evening, was actually in want of ammunition. Napoleon began to with draw his troops at dark on the 22d, into the Lobau; and before day-light on the morning of the 23rd, had effected his retreat: the bridge, 1, (Plate 6) across the third branch of the river was then withdrawn; and as soon as the bridge communicating with the right bank of the river could be repaired, a part of the French army crossed to that side of the Danube.

During all these operations the Archduke Charles made no attempt to reap the fruits of his victory. If a vigorous attack had been made early on the 23d, before the bridges, 1,1X, (Plate 6) from the Lobau to the right bank of the river, were repaired, whilst Napoleon's whole army was crowded in masses upon the island; and, as it afterwards appeared, in want of ammunition, there can be no doubt that very important results might have obtained.