The First Battle of Marengo or Battle of San Giuliano (16 May 1799; Julian calendar: 5 May) saw Republican French soldiers under General of Division Jean Victor Marie Moreau launch a reconnaissance in force against a larger force of Habsburg Austrian and Imperial Russian troops led by Field Marshal Alexander Suvorov.

This War of the Second Coalition meeting engagement occurred near the town of Spinetta Marengo, located just east of Alessandria in northwest Italy.

The commander of the combined Austro-Russian armies, Suvorov massed his forces opposite the fortress city of Alessandria.

[14] On 6 May 1799, Suvorov's left wing crossed the Po at Piacenza and moved southwest toward Bobbio, threatening to cut Moreau off from Genoa.

[15] On 7 May, a 13,865-man Austrian corps was at Castel San Giovanni while General-major Pyotr Bagration with the 5,862-man Russian advance guard was at Voghera, both on the south bank of the Po.

On 9 May, Suvorov's chief of staff, the Austrian General-major Johann Gabriel Chasteler de Courcelles and two battalions chased the French out of the town of Tortona, though its citadel held out.

[16] Probably urged by Grand Duke Constantine Pavlovich of Russia, who had just arrived at the front and was anxious to fight, Rosenberg ignored Suvorov's instructions and crossed upstream of the point where the Tanaro flowed into the Po.

In the Battle of Bassignana on 12 May 1799, Moreau gave the Russians a drubbing and forced them to retreat to the north bank of the Po.

[17] During this time, the Army of Naples under General of Division Jacques MacDonald was moving north from southern Italy and entering the calculations of both Moreau and Suvorov.

On 10 May 1799, MacDonald reached Rome where he left 2,568 of his least fit men under the command of General of Division Gabriel Venance Rey.

On 26 May, the Army of Naples reached Florence where it met troops under General of Division Paul Louis Gaultier de Kervéguen.

[18] As early as 10 May, the Cossack regiments of Denisov, Grekov, and Molchanov, supported by the Kalemin Grenadier Battalion, cleared the French from Marengo.

Starting on 13 May, Suvorov began edging his south bank forces toward the north because he intended to cross the Po and march west toward Turin.

General-major Adrian Karpovich Denisov, commanding the Cossack screen captured a French officer and learned that the enemy incursion was substantial.

[2] General-major Franz Joseph, Marquis de Lusignan, acting division commander in the absence of Michael von Fröhlich, deployed seven battalions and six squadrons of the Lobkowitz Dragoon Regiment Nr.

He claimed that Bagration's troops hung back in a wood and that neither the Cossacks nor the Austrian dragoons were willing to charge the French infantry.

[4] Another account stated that Bagration's troops helped repulse the initial attack, but around noon the Allies began to retreat.

[20] The 16 May battle convinced Moreau to abandon the Italian plain and get his army to the south side of the Ligurian Alps.

[8] Assuming that Suvorov intended to remain where he was, Moreau sent Victor with 7,000 infantry, 200 cavalry, but no artillery on a march to join Pérignon in Genoa.

With Emmanuel Grouchy commanding a flank guard, the French column wended its way through the mountains to Loano on 6 June, from which they shipped their artillery to Genoa.

The Allied army drove the French from Turin into the citadel on 27 May and seized a large number of heavy cannons in the arsenal.

[21] Heinrich von Bellegarde's Austrian corps marched from Switzerland to the area of Alessandria, replacing Suvorov's troops.