The Austrians were full 40,000 strong; while, in the absence of Dessaix and the reserve, Napoleon could, at most, oppose to them 20,000, of whom only 2500 were cavalry.  He had, however, no hesitation about accepting the battle.  His advance, under Gardanne, occupied the small hamlet of Padre Bona, a little in front of Marengo.  At that village, which overlooks a narrow ravine, the channel of a rivulet, Napoleon stationed Victor with the main body of his first line—­the extreme right of it resting on Castel Ceriolo, another hamlet almost parallel with Marengo; Kellerman, with a brigade of cavalry, was posted immediately behind Victor for the protection of his flanks.  A thousand yards in the rear of Victor was the second line, under Lannes, protected in like fashion by the cavalry of Champeaux.  At about an equal distance, again, behind Lannes, was the third line, consisting of the division of St. Cyr, and the consular guard, under Napoleon in person.  The Austrian heavy infantry, on reaching the open field, formed into two lines, the first, under General Haddick, considerably in advance before the other, which Melas himself commanded, with General Zach for his second.  These moved steadily towards Marengo; while the light infantry and cavalry, under General Elsnitz, made a detour round Castel Ceriolo with the purpose of outflanking the French right.

Such was the posture of the two armies when this great battle began.  Gardanne was unable to withstand the shock, and abandoning Padre Bona, fell back to strengthen Victor.  A furious cannonade along the whole front of that position ensued; the tirailleurs of either army posted themselves along the margins of the ravine, and fired incessantly at each other, their pieces almost touching.  Cannon and musketry spread devastation everywhere—­for the armies were but a few toises apart.  For more than two hours Victor withstood singly the vigorous assaults of a far superior force; Marengo had been taken and retaken several times, ere Lannes received orders to reinforce him.  The second line at length advanced, but they found the first in retreat, and the two corps took up a second line of defence considerably to the rear of Marengo.  Here they were, again, charged furiously—­and again, after obstinate resistance, gave way.  General Elsnitz, meantime, having effected his purpose, and fairly marched round Castel Ceriolo, appeared on the right flank, with his splendid cavalry, and began to pour his squadrons upon the retreating columns of Lannes.  That gallant chief formed his troops en echelon; and retired in admirable order—­but the retreat was now general; and, had Melas pursued the advantage with all his reserve, the battle was won.  But that aged general (he was eighty-four years old) doubted not that he had won it already; and at this critical moment, being quite worn out with fatigue, withdrew to the rear, leaving Zach to continue what he considered as now a mere pursuit.