The French Bridging Operations across the Danube in 1809: The Second Attempt: July 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 191 - 199; 201 - 202
But the Archduke still remained, most unaccountably and fatally, inactive; whilst Napoleon repaired his bridges, -- established additional communications -- and was permitted to prepare, unmolested, the foloowing stupendous means by which he afterwards effected the passage of the river, -- formed a junction with the army of the Viceroy of Italy, and gained the decisive victory of Wagram.
Bridges on piles, 3,3 (Plate 6), wide enough for a double file of carriages, were first constructed across both branches of the river, above the bridges of boats, 1, 1X, (Plate 6); and a road made across the island of Lobau to the palce at which the third branch of the river had been crossed. The total length of this bridge was 703 yards; the width 14 1/2 feet. The intervals between the rows of piles were 30 feet. There were 41 ranks of piles in the bridge, 3 (Plate 6), which crossed the channel nearest to the right bank of the river, and 18 rows in the other. Five piles, about 1 foot square, and set about 30 inches apart, were placed in each row, and well braced together. The ridge piece was 9 inches square, 13 feet long, and fixed, by iron clamps, to the piles. The floor of the bridge was about 4 feet above the average level of the river, in floods. -- The velocity of current in the dry season, is about 1 mile an hour; but becomes extremely rapid in floods.
Five beams, about 7 1/2 inches square, were laid from rank to rank of piles, and two rows of planks, about 2 inches thick, formed the floor or roady way. A strong railing was added and beyond it lanthorn posts, erected on both sides.
Immediately below this vast bridge, two others, formed of boats, were prepared, ready to be thrown across both branches of the river; and about 400 or 500 yards above these bridges, stockades of piles, 6,6 (Plate 6), were consructed, to protect the bridges from being injured by any floating bodies that might be drifted down by the current.
About 40 or 50 yards above the large pile bridge, 3 (Plate 6), another of like description, 5 (Plate 6), was constructed across the middle branch of the river, for the passage of infantry only. The length of this bridge was 436 yards. Three piles were set in each rank, and well braced together. Three beams, about 6 1/2 inches in diameter, extended from row to row, and covered with 1 1/2 inch plank. The floor of the bridge was laid about 3 feet about the ordinary flood-level of the water; and a railing constructed on both sides. The piles were driven by pile-engines, constructed on boats of the country. Seven engines were used, working consequently, on seven points at the same time.
Whilst these works were proceeding, and demonstrations making of an intention to attempt the passage of the third branch of the river at the place where Napoleon had previously crossed, vast preparations were making to pass the river below Entzersdorf, and thus to turn the position at Gros Aspern and Esling, which the Austrians were intrenching.
In the channel behind the island Alexander, 16 (Plate 6), which is only 15 yards wide, a bridge, 4 (Plate 6), formed of 14 Austrians bateauz, was prepared, so constructed as to admit of being brought down the winding course of that branch, and, when arrived in the channel below the island, 16 (Plate 6), of being thrown across, by the agency of the current.
To effect this, it was necessary, first, to give this bridge, which was required to be about 170 yards long, a power of flexibility to conform with the windings down which it had to pass, and then to unite and consolidate it sufficiently to resist the strains arising from the manoeuvre it was destined to undergo. It was accordingly prepared in four separate portions -- two formed of four, and the other two of thre boats, the whole secured to each other by ropes whilst descending the narrow channel to its place below the island and all the parts so contrived and fitted, as to be readily and solidly united, in succession, on entering the channel in which the bridge was to be swung across, entire.
Besides this bridge, 5 large ferry boats, each capable of containing 500 men; materials for a bridge of rafts, 2 (Plate 6); and boats sufficient to form another bridge, 1 (Plate 6), were likewise collected in the channel of the river, below the bridge, 1 (Plate 6), another equipage for a bridge of boats was prepared, in two parts; and a number of row-boats collected near the village of Ebersdorf, to receive the troops destined to make the first landing.
These preparations having been completed, Napoleon resumed the offensive on the 30th of June, in the following manner, which confirmed the Austrians in the belief that he would again attempt the passage direct from the Lobau. The batteries 8, 8 (Plate 6), established between the islands 11 and 12 (Plate 6), forced the Austrian posts to withdraw; when some boats, which had been concealed behind the island Massena, 10 (Plate 6), pushed out with some troops, and landed them on the left bank of the river. A bridge of boats,1 (Plate 6), was immediately constructed at the place where the French had formerly crossed, and a tete-de-pont, E (Plate 6), commenced. On the 2d of July, some light infantry were landed on the island, 12 (Plate 6), opposite to Essling, and having established themselves, a bridge of boats, 1 (Plate 6), was laid between that island, and the Lobau; and soonafterwards another bridge constructed, to complete the communication to the left bank: the tete-de-pont, 7 (Plate 6), was then thrown up. These demonstrations succeeded in fixing, exclusively, the attention of the Austrians to those points, upon which, accordingly, a furious fire was directed.
The batteries 8, 8 (Plate 6), consructed in the Lobau and in the small islands of the further branch, having been completed, and armed with nearly a hundred pieces of ordnance, the night between the 4th and 5th of July was fixed upon for the main attack. The weather was extremely propitious to the enterprise; -- a heavy rain increased the obscurity of the time, and thereby concealed the movements of the French.
At about nine o'clock in the evening, the batteries, 8, 8 (Plate 6), all along the offensive line, opened a tremendous fir, under cover of which, the flotilla of row-boats, which had been assembled in the first branch of the river, landed a body of 1500 men, without much opposition, on the left bank of the Danube, near Muhlleuten. The bridge which had been prepared in the middle channel followed the flotilla, and was soon laid across to the main land.
The French troops soon got possession of Entzersdorf, which was set on fire, and the conflgration served to throw light upon the operations of the pontoneers, and greatly facilitated their work. The five large boats immediately came forth, from behind the island Alexander, 16 (Plate 6), and landed their troops (2,500 men) to co-operate with those which had crossed in the flotilla, in establishing a lodgment and in covering the operations of laying the bridges.
The bridge, 4 (Plate 6), already described, followed the five boats; and in proportion as it's parts arrived at the lower end of the island 16 (Plate 6), they were hauled into contiguity by the ropes which held them together and united by the false beams and wedges, as soon as the leading, or lower end of the bridge had arrived at the place at which it was designed to be thrown across. The vast structure, thus consolidated, was then wheeled across the river in a few minutes, by the manoeuvre already described. The operation was eased by hawsers from the near bank to the upper end of the bridge, and by letting go anchors at proper times in succession, and further checking the movement with setting poles. This communication was completed at about eleven o'clock at night.
The bridge of rafts, 2 (Plate 6), followed the bridge 4 (Plate 6), and was laid across from the lower end of the island, 16 (Plate 6), and a bridge of boats, 1, 1+ (Plate 6), constructed a little above. Thus, by two o'clock on the morning of the 5th, the French army possessed six bridges; and whilst the troops were passing these, three others were constructed; -- one from the island Pouzel, 14 (Plate 6); -- the second from below the island Lannes, 15 (Plate 6); -- and the third from theupper end of the island Alexander, 16 (Plate 6). During the night, and very early on the morning of the 5th, the whole of the French army crossed the Danube. The left debouched at about 3,000 yards below Entzersdorf; the right opposite to the village of Muhlleuten. -- The Austrian advanced posts were forced to retire, and Mulleuten taken possession of. -- The French army then extended towards Wittau; -- and, by six o'clock in the morning, had turned the position which the Austrians had taken so much labour to strengthen, upon the supposition that it's front would be attacked! The battle of the 5th continued from seven o'clock in the morning, till nine o'clock at night. In this affair the villages of Aspern, Eslling, Raasdorf, and Gross-Hofen, were carried by the French in succession; and on the 6th Napoleon gained the decisive victory of Wagram.
Throughout the 5th, and during the ensuing night, the Austrians continued to send down the river, floating bodies of various descriptions, to endeavour to destroy the bridges. Several attempts were made with fire-vessels and infernal machines of the following descripiton. The chamber or body of the vessel is bricked up, and filled with powder, shells, &c. The roof or deck is covered with large stones, tarred timber, and other combustible materials. Trigger lines are laid in every direction, from the hull as well as masts, so that any pull or hitch may cause the machine to explode. The best way to deal wich such bodies is to scuttle them by perforating them with large augurs, taking care to touch neither line, rope, nor fitting, but merely impeding their progress towards the bridge as much as possible, whilst filling and sinking.
Napoleon's first attempt to cross the Danub, and to establish himself beyond it, was accompanied with the severe loss, and deserved the failure, which enterprises of pure, open force, upon one point generally meet.; but from the errors committed on the other side, his repulse cost the Austrians equally dear, and prevented them from taking advantage of the very critical position of the French army after it's defeat. The success of the great enterprise was mainly owing to the extraordinary inactivity of the Austrians, in permitting Napoleon to prepare, unmolested, the vast means by which it was effected, and to the great error of not having made arrangements for attacking, with vigour and superior force, the first landing that might be attempted; whilst on the other hand, it must be admitted, that the stratagem the French so ably adopted, to make the Austrians believe that the secondary attempt would be made, where the first had failed, and the admirable management of the bridge department, reflect the highest credit on the authors of those well laid plans and stupendous constructions.
Placed on the Napoleon Series: October 2004