This gave time to Lannes to bring up his division, 5,000 strong, into line between Marengo and Castel Ceriolo.
But when the full force of the Austrian attack was developed about 10 a.m., the Imperialists not only gained Marengo, but threw a heavy column, led by General Ott, against Lannes, who was constrained to retire, contesting every inch of the ground.

Thus, when, an hour later, Bonaparte rode up from the distant rear, hurrying along his Consular Guard, his eye fell upon his battalions overpowered in front and outflanked on both wings.

At once he launched his Consular Guard, 1,000 strong, against Ott's triumphant ranks.

Drawn up in square near Castel Ceriolo, it checked them for a brief space, until, plied by cannon and charged by the enemy's horse, these chosen troops also began to give ground.

But at this crisis Monnier's division of 3,600 men arrived, threw itself into the fight, held up the flood of white-coats around the hamlet of Li Poggi, while Carra St.Cyr fastened his grip on Castel Ceriolo.