Near the end of the day, the French overcame General Michael von Melas' surprise attack, drove the Austrians out of Italy and consolidated Bonaparte's political position in Paris as First Consul of France in the wake of his coup d'état the previous November.

After cutting Melas's line of communications by crossing the river Po and defeating Feldmarschallleutnant (FML) Peter Karl Ott von Bátorkéz at Montebello on 9 June, the French closed in on the Austrian Army, which had massed in Alessandria.

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

Bonaparte realized the true position and issued orders at 11:00 am to recall the detachment under Général de Division (GdD) Louis Desaix while he moved his reserve forward.

[9] Desaix's arrival at around 5:30 pm stabilized the French position, as the 9th Light Infantry Regiment delayed the Austrian advance down the main road and the rest of the army reformed north of Cascina Grossa.

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

The French army then seized Milan on 2 June, followed by Pavia, Piacenza and Stradella, Lombardy, cutting the main Austrian supply route eastward along the south bank of the Po.

As other French forces closed from the west and south, the Austrian commander had withdrawn most of his troops from their positions near Nice and Genoa to Alessandria on the main Turin-Mantua road.

[3] Bonaparte's view was confirmed when Gen. Claude Victor-Perrin, supported by Divisional General Joachim Murat’s cavalry, swiftly evicted FML Andreas O'Reilly von Ballinlough’s Austrian brigade from Marengo village that afternoon.

Long distances from the home bases, from which the regiments drew reinforcements, meant that troop transports had to endure miserable conditions, so only about 15% reached the field army.

In establishing the Army of the Reserve in France, Bonaparte's first move was to overhaul the supply system to provide the troops with regular food and decent uniforms.

Lacking the large superiority in infantry and artillery enjoyed in many Republican campaigns, the core of Bonaparte's reserve was 30,000 men, mostly from the Batavian Republic, who had been used under Guillaume Marie Anne Brune to crush the rebellion in the Vendée.

[19] On the Austrian left, 7,500 men under FML Peter Ott waited for the road to clear before heading for the village of Castel Ceriolo well to the north of the French positions.

First, at 8 am, Melas hurled FML Karl Joseph Hadik von Futak's division (four battalions) at Victor's defenses, supported by Frimont's advance guard battery along the stream.

Finally, as the French position was reinforced by François Étienne de Kellermann's cavalry and Jean Lannes's formation was on the way, FML Ferdinand Johann von Morzin's elite grenadier division was sent in to attack Marengo village.

[21] Melas also committed a serious tactical blunder, detaching Generalmajor (GM) Nimptsch's brigade of 2,300 hussars and two artillery batteries back over the Bormida bridge to block the corps of General Louis Gabriel Suchet, which was mistakenly reported around 9 am from Acqui Terme to be approaching Alessandria from the south.

GM Friedrich Joseph Anton von Bellegarde’s part of Kaim's division had crossed the Fontanone north of Marengo and occupied La Barbotta farm.

A small part of the 6ème Légère (6th Light Infantry Regiment) occupied Castel Ceriolo to the north, but soon Ott's lead units took it around 11:30 am and began putting pressure on the French right flank.

As they came up, GdD Jean-Charles Monnier's division and the Consular Guard were committed to extend and shore up the French right, rather than to try to hold Marengo where Victor's men were running short of ammunition.

GM Christoph von Lattermann’s grenadiers crossed to engage Olivier Macoux Rivaud de la Raffinière’s two demibrigades defending Marengo village, while Bellegarde and Frimont's four squadrons split Watrin off.

Although Rivaud retook the village, O’Reilly had taken Stortiglione by 2:00 pm, and in the north, Ott prepared to send FML Joseph von Schellenberg’s column to support Gottesheim.

The Austrian centre formed into a massive pursuit column in order to chase the French off the battlefield, with the advance guard commanded by GM Franz Xaver Saint-Julien.

[21] On the Austrian right wing, O'Reilly wasted time hunting down a 300-man French detachment led by Achille Dampierre (which was finally captured) and moved southeast.

[26] However, Desaix, in charge of the force Bonaparte had detached southwards, had hastened his advance and reached a small road junction north of Cascina Grossa (3 km west of San Giuliano).

Boudet and the 9ème Légère (9th Light Infantry Regiment) were quickly moved on to the exit from the main vine belt, where they surprised the head of Saint-Julien's column.

As the mob of terrified cavalry stampeded past them, the exhausted Austrian infantry of the main body lost heart, provoking a wild rush to the rear.

[30] Ott with the Austrian left failed to intervene and found his retreat through Castel Ceriolo blocked by French troops advancing northwest from the centre, but managed to fight his way back to the Bormida bridgehead.

Melas, trapped in Alessandria with his hopes of breaking through to the east shattered, sent the same evening to Vienna a message in which he explained that the "charge of Kellermann had broken the soldiers and this sudden and terrible change of fortunes finished by smashing the courage of the troops.

Berthier suggests that time had to be given to Desaix and Boudet's division to occupy their positions: "The enemy general misinterpreted this maneuver and thought the army was in full retreat, while in reality it was only executing a movement of conversion.

[citation needed] Napoleon sought to ensure that his victory would not be forgotten, so, besides the propaganda campaign, he entrusted General Chasseloup with the construction of a pyramid on the site of the battle.