The Campaign of Marengo, With Comments

by Herbert H. Sargent

In order to understand clearly the strategical problems presented by these operations, it is necessary to keep in mind the positions of the French and Austrian forces, and the topography of the country in which these manœuvres and battles took place.

Picture to yourself the French forces occupying Switzerland and France on the left bank of the Rhine as far north as Strasburg; and on the opposite side of the river, the long line of the Austrians, their left on the borders of eastern Switzerland and in the Tyrol, their right extending far to the north, even to Mayence, and their centre, forming the main part of the Austrian army, occupying the Black Forest with advanced brigades and outposts pushed forward almost to the banks of the Rhine. Picture to yourself the triangular mountain system of the Black Forest, lying in the angle of the Rhine between Lake Constance and Strasburg, like a huge bastion, its south and west sides steep and rugged, and its hills and mountains covered with a dark forest of pines and firs. Picture to yourself the fifteen thousand Austrians, under Kienmayer, along the rugged west face of this mountain group; the forty thousand, under the immediate command of Marshal Kray, lying on the eastern slope of this great barrier of mountains and hills; the reserve of nineteen thousand at Stokach on the direct road between Schaffhausen and Ulm, and but a day's march from the French in Switzerland; the magazines at Stokach, Engen, Mosskirch, and Biberach, upon which Kray depended for his supplies; and the immense intrenched camp at Ulm, which, lying in his rear upon the Danube, was the temporary base of the Austrians in the Black Forest.

By occupying all the valleys, roads, and prominent points in the theatre of operations, the Austrians expected to hold military possession of the country. Their system of war was to form a chain of posts—a cordon—along the line to be occupied; and by this means they expected to prevent the advance of the enemy. Thus the Austrian army was scattered over a great extent of country from the Tyrol to Lake Constance, thence through the Black Forest to the Main River. Their line was more than three hundred miles in extent.

Kray had extended his right wing as far north as Mayence, in order to protect the troops in the Black Forest from a French attack on that side. Since Moreau held the line of the Rhine, possibly he might attempt to cross at Mayence, thence, using the Main River to screen his movements, might march to Wurtzburg, and from that point march south on Ulm. By such a manœuvre, he could sever Kray's communications, take the Austrians in rear in the Black Forest, and compel them to fight with their face towards Vienna, in order to recover their communications. But, in order to protect himself on this side, Kray had extended Starray's corps too far north; it consisted of but sixteen thousand soldiers, and was so scattered from Mayence to Renchen, a distance of one hundred miles, that it was weak at all points. Moreover, it was so far distant from the main Austrian forces in the Black Forest that it could neither readily aid them in case they should be attacked in force, nor be readily aided by them should Moreau attempt to make a flank movement against the Austrian right.

But a greater fault in the situation of the Austrian army was due to the fact that the Aulic Council had given orders that Kray's left wing, under the Prince de Reuss, should remain on the borders of eastern Switzerland and in the Tyrol. This wing could not, therefore, re-enforce Kray in the Black Forest. With his left thus paralyzed by the action of the Aulic Council, Kray found himself hampered throughout the campaign.

Kray committed another error in collecting immense magazines at Stokach; for this place, being but a day's march from the French forces in Switzerland, was not only the most vulnerable but also the most important point occupied by the Austrians. Lying in a gap between Lake Constance and the mountains of Switzerland on one side, and the Black Forest on the other, and being on the direct road from Schaffhausen to Ulm, it was, so to speak, the vital point of the long Austrian line. Along this route the French would be most likely to advance into Germany; for they could ascend the Rhine by the river roads, thence proceed to Stokach, and thus avoid the great natural barrier of the Black Forest. Moreover, by adopting this plan there were great strategical advantages to be gained.

First: Should the French capture Stokach, they would permanently separate the Austrian left from the centre and right. Thus they would divide the forces of the Austrians, and might thereafter be able to defeat them in detail.

Second: Should the French capture Stokach, they would be in a favorable position to march north against the Austrians and sever their communications with Ulm. In this position, the French, if defeated, could fall back to Schaffhausen, and recross the river there with little or no danger of losing their communications; but the Austrians, being obliged to form their line of battle parallel, or nearly so, to the roads leading to their base, would, if defeated, be thrown back into the Black Forest, where doubtless they would be captured or destroyed. In short, the success of the French at Stokach would enable them to carry out two great principles of war: not only would they divide the forces of their enemy, and thus eventually be able to defeat them in detail; but they would gain a position where they could threaten the communications of Kray in the Black Forest without exposing their own to his attacks.

In the angle of the Rhine between Lake Constance and Strasburg, Kray had but eighty thousand soldiers. Upon this force he had to rely in order to repel any attack which the French might make in the Black Forest; for his extreme right, under Starray, and his left, under Prince de Reuss, were too far away to support his centre before the French could unite to attack it. Bearing in mind that the French crossed the Rhine with one hundred and four thousand soldiers, we perceive that the opportunity was offered Moreau of bringing superior numbers against Kray. In other words, should both opposing commanders succeed in uniting all their available forces upon a battle-field in the Black Forest, Moreau would outnumber Kray in about the proportion of four to three. As the first principle of war is to be stronger than the enemy at the vital point, it is always of the greatest importance that no plan of campaign be adopted, which shall, at the very start, allow the enemy to bring superior numbers on the battle-field.

In withdrawing seven thousand men from Stokach to replace the seven thousand sent from Villingen to re-enforce Kienmayer, Kray committed another error. In fact, at the outset of the campaign he weakened the garrison of the most important point of the whole Austrian line, by sending away more than one third of the troops there. Thus, unconsciously, he played into the hands of his adversary; for at the very time that these troops were leaving Stokach, Moreau was so regulating his manœuvres as to make in the near future his first great effort against Kray at or near that place.