The Battle of Marengo is fought on June 14, 1800, between French forces under Napoleon Bonaparte and Austrian forces near the city of Alessandria, in Piedmont, Italy.

Near the end of the day, the French overcome General Michael von Melas's surprise attack, driving the Austrians out of Italy and enhancing Napoleon's political position in Paris as First Consul of France in the wake of his coup d’état the previous November.

Surprised by the Austrian advance toward Genoa in mid-April 1800, Bonaparte hastily leads his army over the Alps in mid-May and reaches Milan on June 2.

After cutting Melas’ line of communications by crossing the River Po and defeating Feldmarschallleutnant (FML) Peter Karl Ott von Bátorkéz at Montebello on June 9, the French close  in on the Austrian army, which has massed in Alessandria.

Deceived by a local double agent, Bonaparte dispatches large forces to the north and south, but the Austrians launch a surprise attack on June 14 against the main French army under General Louis Alexandre Berthier.

Initially their two assaults across the Fontanone stream near Marengo village are repelled, and Gen. Jean Lannes reinforces the French right.

Bonaparte realizes the true position and issues orders at 11:00 am to recall the detachment under Général de Division (GdD) Louis Desaix, while moving his reserve forward.

On the Austrian left, Ott’s column has taken Castel Ceriolo, and its advance guard moves south to attack Lannes’ flank.

Melas renews the main assault and the Austrians break the central French position.

By 2:30 pm the French are withdrawing and Austrian dragoons seize the Marengo farm.

Bonaparte has by now arrived with the reserve, but Berthier’s troops begin to fall back on the main vine belts.

Knowing Desaix is approaching, Bonaparte is anxious about a column of Ott’s soldiers marching from the north, so he deploys his Consular Guard infantry to delay it.

The French now withdrew steadily eastward toward San Giuliano Vecchio as the Austrians form a column to follow them in line with Ott’s advance in the northern sector.

Desaix’s arrival around 5:30 pm stabilizes the French position, as the 9th Light Infantry Regiment delays the Austrian advance down the main road and the rest of the army reforms north of Cascina Grossa.

As the pursuing Austrian troops arrive, a mix of musketry and artillery fire conceals the surprise attack of Général de Brigade (GdB) François Étienne de Kellermann’s cavalry, which throws the Austrian pursuit into disordered flight back into Alessandria, with about fourteen thousand killed, wounded or captured.

The French casualties are considerably fewer, but include Desaix.

The whole French line chases after the Austrians to seal une victoire politique (a political victory) that secures Bonaparte’s grip on power after the coup.

It will be followed by a propaganda campaign that will seek to rewrite the story of the battle three times during Napoleon’s rule.