Battle of Marengo

On 14 June 1800 (25 Prairial Year VIII), near Alessandria in Piedmont, Bonaparte, then First Consul, reversed a surprise attack by Field Marshal Melas's Austrian army. After a difficult morning in which Victor and Lannes gave ground, Desaix's corps arrived and a late-day counterattack turned impending French defeat into decisive victory.

In the spring of 1800 Bonaparte had been First Consul for six months and his position remained fragile against generals hostile to him: he needed a decisive victory. In Italy, Melas was besieging Genoa and had driven the French back. Bonaparte formed a reserve army and crossed the Alps on 23 May to fall on the Austrian rear; Murat occupied Milan on 2 June. But Masséna's capitulation at Genoa on 4 June wrecked the encirclement plan. Fearing Melas would escape him, Bonaparte then scattered his forces across a wide front: Desaix set off for Novi Ligure with 6,000 men, La Poype northwards. It was this overstretched deployment that the Austrians attacked on 14 June.

The Austrian offensive opened at nine in the morning with an attack on the village of Marengo. Victor's and Lannes's divisions fought a defensive retreat until about two o'clock, yielding ground step by step along the Fontanone. Melas, believing himself the victor, left the field and handed the pursuit to his staff. Around five o'clock Desaix, hastily recalled, arrived with fresh divisions and engaged the Austrian column strung out in pursuit; Kellermann's cavalry charge took the column in flank and broke its ranks. Desaix was killed in this decisive counter-attack.

The Austrians left some 9,400 dead and wounded and 8,000 prisoners; the French counted nearly 4,700 casualties and 900 missing, Desaix among them. The victory, won in extremis, allowed Bonaparte to impose the Convention of Alessandria, which cleared the Austrians out of northern Italy, and led on to the Treaty of Lunéville in 1801. Above all it eclipsed the successes of his military rivals and consolidated his authority over the Consulate — the battle would later be extensively rewritten to erase its early disorder.