Besieged on land by 24,000 troops led by Peter Karl Ott von Bátorkéz and at sea by a Royal Navy squadron under Lord Keith, famine reduced the defenders to starvation.

[4] Schérer was replaced in command by GD Jean Victor Marie Moreau but the French were beaten at the Battle of Cassano on 27–28 April 1799.

The Army of Italy commander GD Jean-Étienne Championnet wanted to abandon Genoa, but the Directory refused to allow this.

[12] On 9 October 1799, GD Napoleon Bonaparte returned to France from Egypt[13] and entered into a conspiracy to overthrow the unpopular Directory.

[18] Massena assigned 4,000 soldiers under GD Louis Marie Turreau to defend the Mont Cenis pass west of Turin.

[17] Soult's corps included divisions led by Miollis, GD Honoré Gazan, and GD Jean-Antoine Marbot, while Suchet's corps consisted of four small divisions under GDs Bertrand Clausel, Jean Pierre Pouget, Pierre Dominique Garnier, and Philippe Romain Ménard.

This would provide a chance for the Austrian army in Germany under Paul Kray (promoted to Feldzeugmeister) to invade France by striking through the Belfort gap.

[20] Melas assigned FML Konrad Valentin von Kaim and 31,000 troops to watch the Alpine passes to the north and west.

Melas split his force in two, personally leading 27,500 troops while FML Anton von Elsnitz led 21,100 soldiers.

[23][note 1] Melas' offensive began on 4 April 1800, as he strove to seize the coastal highway, cutting the Army of Italy in two.

Far to the northwest at Monte Cenis on 8 April, an Austrian raid on Turreau's division surprised and captured the French 15th Light Infantry Regiment in a body.

On 9 April at the Bochetta Pass, Hohenzollern and 10,000 Austrians defeated 3,500 soldiers from Gazan's division, inflicting 1,000 casualties on the French.

[24] Leaving 8,000 soldiers to defend Genoa, Massena and Soult attacked toward the west, while Suchet's troops pressed to the east.

Melas kept his composure and was able to hold his central position, though his troops suffered casualties of 276 officers and 8,037 rank and file between 6 and 19 April.

[30] Suchet finally stopped retreating at the Var River where his chief of engineers GB Jacques Campredon constructed a fortified bridgehead on the east bank.

[32] On 14 May, Bonaparte's Army of Reserve began crossing the Great St Bernard Pass into northwestern Italy.

Worried about reports coming from the north, Melas left Elsnitz with 17,000 Austrians on the Var River and marched with 9,000 men to Turin which he reached on 25 May.

[25] The siege was supported by a British naval squadron that consisted of HMS Minotaur, Phoenix, Mondovi, Entreprenante, and the tender Victoire, all under the command of Vice Admiral George Elphinstone, 1st Viscount Keith.

[25] The assault on the Deux-Frères redoubt on Monte due Fratelli was led by Generalmajor (GM) Nikolaus Pálffy ab Erdöd.

Massena then organized a series of afternoon counterattacks, including one that rescued Colonel Georges Mouton, commander of the 3rd Line.

[39] On 2 May 1800, Colonel Honoré Charles Reille delivered a message to Massena from Bonaparte that outlined his strategy to enter Italy across the Alps and strike the Austrians from behind.

[40] Massena continued to hold out despite large numbers of French soldiers and civilians starting to die from starvation and typhus.

On 2 June, Ott received orders from Melas to abandon the siege and march to join the main army.

[42] Massena demanded that his soldiers would be free to begin fighting as soon as they reached French-held territory and insisted on other privileges as well.

[45] Before leaving, Massena told GM Franz Xaver Saint-Julien that the French would be back in Genoa within three weeks.

Melas was hopelessly isolated by superior forces and was compelled to negotiate the Convention of Alessandria where he gave up 12 fortresses.