The Campaign of Marengo, With Comments

by Herbert H. Sargent

Third: Owing to the fact that he had deceived Melas as to the existence and destination of the Army of Reserve, Bonaparte believed that he could cross the Alps with this army, march to Milan, and there be joined by Moncey's corps before Melas should discover his plan.

Fourth: Inasmuch as all the roads leading from the French frontier to the Austrian base of operations on the Mincio passed through the country lying between Milan and Placentia, he hoped that, by adopting this plan, he would be able to assemble his forces in this space, seize the roads there, and thus completely sever the Austrian communications and place Melas in a position where he must fight under a great disadvantage. With the French in possession of these roads, Melas would be compelled to concentrate and fight in order to recover his communications and save his army. In doing so he would be forced to raise the siege of Genoa and to abandon the attempted invasion of France.

Fifth: Should Bonaparte succeed in concentrating his forces as here set forth, the advantages of his position would be immense. The St. Gothard and Simplon routes in his rear would give him a safe retreat into the great stronghold of Switzerland in case of defeat; the Ticino would protect his right flank, the Adda his left; and the fertile plains of the Po would furnish the necessary supplies for his men and animals, while he was making ready to fight the Austrians or awaiting their attack.

Such are the principal reasons that decided Bonaparte to march the Army of Reserve into that part of Italy lying between the Po and Switzerland. But, having decided on this course, he had yet to determine whether he would lead the Army of Reserve across the Great St. Bernard, or march it into Switzerland and thence descend into Italy by way of the St. Gothard or the Simplon. It will be remembered that for a time he was undecided as to what course to take, and did not fully make up his mind until some time after the Army of Reserve had assembled at Lake Geneva.

In several respects the safest course that Bonaparte could have taken was to conduct his army into Switzerland, unite it with Moncey's corps, and march on Milan by way of the St. Gothard Pass. Had he adopted this course, he would have entered Italy with united forces along a single line of operations, and would have avoided the dangerous flank march from Ivrea to Milan within the enemy's territory. At this time his objective was Milan. His purpose was to assemble his army and the corps of Moncey in that vicinity. By crossing the Great St. Bernard with the Army of Reserve, while Moncey marched by way of the St. Gothard Pass, Bonaparte gave Melas the opportunity of concentrating the Austrian forces between the Army of Reserve and Moncey's corps, and of crushing each in turn with superior numbers.

In the comments on Moreau's operations in Germany, it has already been remarked that it is always a dangerous operation to attempt a concentration upon some designated place within the enemy's lines, for, as a rule, the enemy can mass his forces there more rapidly than the commander of an invading army; that in fact many a campaign has failed because the commanding general has attempted to concentrate his scattered forces upon some point within the territory held by the enemy. By so doing he gives the enemy a chance to assemble his forces between the separated columns of the attacking army, and to bring superior numbers against each column in succession. Yet in these operations Bonaparte not only committed this error, not only did what he had condemned Moreau for doing, but he also violated the principle which he himself had so often set forth and had so often exemplified, namely, not to invade a country with a double line of operations.

Why then did Bonaparte take this course? To answer satisfactorily this question it is necessary to bear in mind that, at this time, Suchet was fighting greatly superior forces on the Var, and that Masséna was in desperate straits at Genoa. The problem before Bonaparte was not merely to assemble his forces in the vicinity of Milan, but so to assemble them there as to stop the projected invasion of France and bring speedy relief to Masséna.

The most direct route from Lake Geneva to Milan is by way of the Great St. Bernard Pass, and thence through northern Italy. Had, therefore, Bonaparte taken the longer route through Switzerland by way of the St. Gothard, the Austrians, in the meantime, could have forced the crossings of the Var, and have compelled Masséna to surrender. Indeed, these events were the more likely to happen, inasmuch as the Army of Reserve, during its march through Switzerland, would not threaten in the least the Austrian communications.

The importance of crossing the Great St. Bernard with the Army of Reserve is seen in the fact that no sooner had French troops appeared in the valley of the Aosta than Melas at once withdrew ten thousand men from Suchet's front and ordered them to march on Turin. Thus, by the mere crossing of the Great St. Bernard with the Army of Reserve, the projected invasion of France was brought to an end. It was inevitable that such should be the case; for as soon as the French appeared in the extreme northern part of Italy, their mere presence there threatened the communications of the Austrians. It was therefore necessary that Melas should abandon the invasion of France, in order to destroy, if possible, the French troops that were threatening his rear. In war, it will ever be thus. No commander can afford to take the risk of pushing forward to new conquests so long as his communications are seriously threatened by his enemy.