First: The movement of the French right on Stokach and Engen threatened the communications of Kray, without in the least exposing the communications of Moreau to an Austrian attack. In accordance with a maxim of war, proved by experience, Kray would therefore have abandoned any intended attack upon Ste. Suzanne, in order to fight for the preservation of his own communications. "The commander," says Hamley, "who finds himself on his enemy's rear, while his own is still beyond the adversary's reach, may cast aside all anxiety for his own communications, and call up every detachment to the decisive point, certain that the enemy will abandon his own designs, in order, if possible, to retrieve his position." Had Moreau appreciated this fact, he could have safely united three of his corps near Stokach, and have overwhelmed the Austrians with superior numbers.
Second: Though Ste. Suzanne seemed to be in a dangerous position, he was not so in reality. In fact, had Kray attacked Ste. Suzanne in force near Neustadt, he would have given the French at Engen and Stokach an immense advantage; for the farther he proceeded into the Black Forest towards France, the more easily could the French sever his communications and destroy or capture his army.
Third: Instead, therefore, of Moreau's being fearful lest the Austrians should concentrate against Ste. Suzanne, he should rather have hoped to see them carry out this movement. But, in either case, he should have strongly re-enforced his right by every means in his power.
After the battle of Engen, Moreau continued to commit errors. At Mosskirch he attacked the Austrians with but fifty thousand men. At the beginning of the battle Kray had but forty thousand men, yet before it ended he was strongly re-enforced. During the battle St. Cyr's corps was near Geisingen and Ste. Suzanne's at Donaueschingen. Thus, for the second time, Moreau fought the Austrians with two of his corps absent. Moreover, they were far away on his left flank, when they should have been near him, or on his right flank, where they would have been able to overwhelm Kray, and sever his communications with Ulm. Had Moreau re-enforced strongly his right, and attacked Kray at Mosskirch with his four corps, or even with three of them, who can doubt what the result would have been? Undoubtedly he would have destroyed the Austrians between his army and the Danube, and could then have rapidly crossed the river and have intercepted the corps of Kienmayer and Starray. In truth, Moreau's faults allowed Kray to escape, when he should have been destroyed. They allowed him to seek safety in Ulm, where for several weeks he was able to make a successful stand.
This part of Moreau's campaign, from the time he left Schaffhausen till he arrived at Ulm, was a series of errors. Though in a measure successful in his operations, he was outgeneralled by Kray. In this campaign every opportunity was offered Moreau to win a great name, but he did not possess the necessary military ability. He was in command of the largest and best equipped army of France; instead of gaining merely two or three indecisive victories and forcing Kray back to Ulm, he should have united his forces, crushed his enemy, severed Kray's communications, and captured his army; and then should have marched on Vienna and compelled the Austrian Emperor to sue for peace. But such fame was not for him. It was reserved for that greater genius, who, beyond the Alps, on the plains of Italy, should, with inferior forces, do greater deeds and accomplish far greater results. It was reserved for him who, daring to follow in the footsteps of the great Carthaginian, was destined to startle the world by the splendor of his achievements.
If there was one distinguishing peculiarity in Napoleon's system of war, it was that of so manœuvring as to divide the forces of his enemy and then to defeat them in detail. In the early part of his career he was fortunate in being opposed to the Austrians, whose system of scattering their troops enabled him to defeat separately the fragments of their armies. He believed in concentrating his troops. He was, in fact, the greatest exemplar of concentration that the world has ever known. His plan was to mass his forces against some vital point of the enemy, and to attack him on one line, and in such a direction as to place him at a disadvantage. If the enemy's line was too much extended, he struck at the centre and broke through it, then attacked and defeated in detail the separated parts. If the enemy advanced to attack with his army separated into parts by impassable obstacles, Napoleon manœuvred so as to crush in succession these isolated parts before they could unite. In this way, by fighting a part of the enemy's army at one time, he was nearly always stronger than the enemy on the battle-field. With him this was the important point. His rapid marches, his strategical manœuvres, his combinations, had nearly always this object in view. He believed that success in battle depended principally on numbers. "God," said he, "is on the side of the heaviest battalions."
But notwithstanding the fact that this was the distinguishing peculiarity of Napoleon's system of war, yet he did not always follow this system. Several times in his career he won a great victory by making a flank movement against his enemy. Such a movement was made at Marengo, at Ulm, and at Jena.
Between these two methods of attack there is, as a rule, this difference. By striking at the centre of the enemy's line, his army can be separated into two parts, and then be defeated in detail. In this case the aim is so to manœuvre as to outnumber the enemy on the battle-field. But by striking at the flank, the enemy is often given the opportunity of concentrating his forces. Even if one flank is defeated, it can fall back upon the other, and perhaps even then make a successful stand against the attacking army. In this case the advantages generally aimed at are to threaten or sever the communications of the enemy, and to force him to fight a battle where a defeat will ruin his army. From the foregoing, it is evident that these two methods of attack have a tendency to produce opposite results. A direct attack upon the enemy, if successful, breaks up and scatters his forces. On the other hand, a flank attack gives him a chance to concentrate, but at the same time places him in a position where a defeat will ruin him.