The first attacks of the Austrians were repulsed, but with loss and difficulty. At ten in the morning Ott came up, and attacked Lannes's flank. The fighting grew ever hotter and more desperate, and the news from Desaix was that it would be four in the afternoon before he could arrive. Bonaparte called in his small reserve, under Monnier, to strengthen Lannes; but it was of no avail. By midday the French were driven out of Marengo, their front was broken, and their columns were in full retreat to the eastward toward San Giuliano. The First Consul was in despair, and as a last resource sent in eight hundred of the consular guard. For the first hour of the afternoon the retreat was stayed. But the French were soon outflanked on their left by Austrian cavalry, and again began to withdraw. Bonaparte sat by the roadside, and, swishing his riding-whip, called to the flying men to stand and wait for the reserve, a body of troops which did not exist. Seven thousand soldiers--a fifth of his entire available force--had, it is estimated, already fallen. Desaix was not yet within reach. Melas believed he had won the day. Perhaps if the weight of seventy years, and a slight wound, had left the Austrian commander personally less exhausted, he would, in spite of having long endured the heat, fatigue, and dust, have carried his victorious columns onward until he had utterly scattered his enemy. As it was, he deputed the final discomfiture of the disorganized yet slowly, stubbornly retreating Frenchmen to Zach, his chief of staff, and returned to Alessandria. His command, ordered in single main column, followed directly on, while Ott, with a minor one, deviated toward the left to seek a parallel line of pursuit.