From this table it appears that the ratio of the two arms at these sieges, making the comparison on the basis of our own organization, is about the same as for the present French army in Algeria, or a little more than five of engineers to six of artillery.
Thus far we have spoken of the field-operations of engineer troops in connection with fortifications, alluding only incidentally to the use of military bridges and the passage of rivers. In the early wars of the French Revolution the want of pontoniers was severely felt, and from the deficiency of this branch of service, the operations of the French generals were on several occasions very much restricted. The evil was afterwards remedied in a great degree by the introduction of several battalions of ponioniers in the regular army organization. On many occasions, during his wars, did Napoleon feel and acknowledge the importance of these troops; but on none, perhaps, was this importance more clearly shown than in the passage of the Beresina during his retreat from Moscow with the wreck of his army. The Russians had cut the bridge of Borisow and taken position in great strength on the right bank of the river, both at this point and below; the French, wearied with long and difficult marches, destitute of artillery, provisions, and military stores, with a wide and deep river in front, and a powerful enemy on their flank and rear, benumbed by the rigors of a merciless climate, and dispirited by defeat—every thing seemed to promise their total destruction. "General Eblé," says an English general officer, in his remarks on this retreat, "who, from the beginning of the campaign, had made all the arrangements for the equipment and construction of military bridges, was specially charged with the important duty of providing for the passage of this river; and he discharged that duty with a degree of forecast and ability to which certainly Napoleon owed his escape and the wreck of his army its safety. General Eblé had begun to prepare, at Smolensko, for the difficulties which he foresaw in this operation. He formed, with every care, a train sufficient for the transport of all the tools and stores that might be required; and, further to provide against casualties and accidents, every man belonging to the companies of pontoniers was obliged to carry from Smolensko a tool or implement of some kind, and a proportion of nails: and fortunate was it for the army that he did so; for such was the difficulty in getting through the carriages containing stores, that only two forge-wagons and six caissons of tools and nails could be preserved. To these the general added a quantity of iron-work taken from the wheels of carriages that were abandoned on the march. Much was sacrificed to bring off these valuable materials for making clamps and fastenings, but, as Segur observes, that exertion 'sauva l'armée.'"
But it is not always in the possession of a thing that we are most likely to appreciate its utility; the evils and inconveniences resulting from the want of it not unfrequently impress us most powerfully with its importance and the advantages to be derived from its possession. A few examples of this nature, drawn from military history, may be instructive. We need not go back to the disastrous passage of the Vistula by Charles XII., the failure of Marlborough to pass the Dyle, and Eugene to cross the Adda in 1705, nor of the three unsuccessful attempts of Charles of Lorraine to cross the Rhine in 1743. The wars following the French Revolution are sufficiently replete with useful instruction on this subject.[[39]]
Before recurring to these, it might be useful to give one example, as it is often referred to, in the campaign of 1702. It was deemed important for the success of the campaign to attack the Prince of Baden in his camp at Friedlingen. Accordingly, a bridge was thrown across the Rhine at Huningen, the passage effected, and the victory gained. But Villars was several times on the point of losing all for want of a sufficient ponton equipage. Having but a single bridge, the passage was necessarily slow; the artillery and stores were frequently interrupted by the infantry hurrying to the field of battle; disorder ensued, and the whole movement was retarded; Villars could bring only a small part of his artillery into action, and towards the close of the battle the infantry were in want of ammunition: moreover, the whole operation had nearly failed from the attempt of the enemy to destroy this bridge, but the skill of the French pontoniers saved it. We here remark, 1st, the passage secured to Villars an important victory; 2d, from having an inefficient bridge-equipage his whole army was placed in great peril, and the operation had nearly failed; 3d, if the Prince of Baden had possessed a skilful corps to oppose that of Villars, this single bridge would have been destroyed, and the army cut to pieces; 4th, the skill of the little corps of French pontoniers saved the bridge, and of consequence, the army.
In 1794 so great was the disorder in the direction of affairs, that the boats of the bridges across the Wahal and the Rhine were disposed of for commercial purposes; and in the beginning of 1795, says Jomini, "the conquerors of Belgium and Holland had not even a bridge equipage, at a time too when the success of the campaign depended solely on the means of crossing a river." A few boats were procured from the Wahal and the Meuse, and others manufactured in the forests of the Moselle; but "these operations consumed precious time, and four months thus passed away in preparations." Even after other things were all ready, the army was obliged to wait thirty days for the arrival of boats for ponton bridges; during this delay the Austrians strengthened their position, and with very little exertion they might easily have prevented the passage.
In 1796, profiting by the errors of the former campaigns, the French collected more suitable bridge equipages, and the two armies passed the Rhine at Neuweid and Kehl without loss or delay. The latter of these passages has often been referred to as a model for such operations, and certainly does credit to the general who directed it. But Moreau's bridge equipage having been destroyed during this disastrous campaign, his operations the following year were considerably delayed in preparing a new one, and even then he was under the necessity of seizing all private boats that could be found within reach; but the difficulty of collecting and using boats of all sizes and descriptions was so great as entirely to defeat his plan of surprising the enemy on the opposite bank of the river. The necessity of co-operating with Hoche admitted of no further delay, and he was now obliged to force his passage in the open day, and in face of the enemy. Undertaken under such circumstances, "the enterprise was extremely sanguinary, and at one time very doubtful;" and had it failed, "Moreau's army would have been ruined for the campaign."
Napoleon's celebrated passage of the Po, at Placentia, shows plainly how important it is for a general to possess the means of crossing rivers. "I felt the importance of hastening the enterprise in order not to allow the enemy time to prevent it. But the Po, which is a river as wide and deep as the Rhine, is a barrier difficult to be overcome. We had no means of constructing a bridge, and were obliged to content ourselves with the means of embarkation found at Placentia and its environs. Lannes, chief of brigade, crossed in the first boats, with the advanced guard. The Austrians had only ten squadrons on the other side, and these were easily overcome. The passage was now continued without interruption, but very slowly. If I had had a good ponton-equipage, the fate of the enemy's army had been sealed; but the necessity of passing the river by successive embarkations saved it."
In the campaign of 1799, the Archduke attempted to pass the Aar, and attacked the French on the opposite side, but for want of suitable equipage his operation was delayed till the enemy had collected sufficient forces to intercept the passage; he was now obliged to enter into a stipulation for a suspension of hostilities, and to withdraw his bridges.