General Melas, observing the French in retreat, left the direction of the movements of his army to the chief of his staff, and retired to Alexandria to repose from the fatigues of the day. Colonel Zach, equally convinced with his general that the French army was completely broken, and consisted only of fugitives, formed the divisions in column of route.
By this arrangement, the imperial army prepared to enter upon its victorious march in a formation not less than three miles in depth.
It was near four o’clock when General Desaix rejoined the French army with his division. His presence restored in some degree an equality between the contending forces; and yet Napoleon hesitated for a moment whether to resume the offensive, or to make use of this corps to secure his retreat. The ardor of the troops to return to the charge, decided his irresolution. He rode rapidly along the front of his divisions, and addressing the soldiers—“We have retired far enough for to-day,” said he; “you know I always sleep upon the field of battle!”
The army, with unanimous shout, proclaimed to him a promise of victory. Napoleon resumed the offensive. The Austrian advance guard, panic-struck at the sight of a formidable and unbroken body presenting itself suddenly at a point where, a few moments before, only fugitives were to be seen, went to the right about, and carried disorder into the mass of its columns. Attacked immediately afterward, with impetuosity, in its front and flanks, the Austrian army was completely routed.
Marshal Daun experienced nearly the same fate as General Melas, at the battle of Torgau, in the campaign of 1760.
The position of the Austrian army was excellent. It had its left upon Torgau, its right on the plateau of Siptitz, and its front covered by a large sheet of water.
Frederick proposed to turn its right in order to make an attack upon the rear. For this purpose he divided his army into two corps, the one under the orders of Ziethen, with instructions to attack in front, following the edge of the water; the other under his own immediate command, with which he set out to turn the right of the Austrians. But Marshal Daun having had intimation of the movements of the enemy, changed his front by countermarching, and was thus enabled to repel the attacks of Frederick, whom he obliged to retreat. The two corps of the Prussian army had been acting without communication. Ziethen, in the meantime, hearing the fire recede, concluded that the king had been beaten, and commenced a movement by his left in order to rejoin him; but falling in with two battalions of the reserve, the Prussian general profited by this reinforcement to resume the offensive. Accordingly he renewed the attack with vigor, got possession of the plateau of Siptitz, and soon after of the whole field of battle. The sun had already set when the King of Prussia received the news of this unexpected good fortune. He returned in all haste, took advantage of the night to restore order in his disorganized army, and the day after the battle occupied Torgau.
Marshal Daun was receiving congratulations upon his victory, when he heard that the Prussians had resumed the offensive. He immediately commanded a retreat, and at daybreak the Austrians repassed the Elbe with the loss of twelve thousand men, eight thousand prisoners, and forty-five pieces of cannon.
After the battle of Marengo, General Melas, although in the midst of his fortresses and magazines, saw himself compelled to abandon everything, in order to save the wreck of his army.