Campaigns of 1800 in the French Revolutionary Wars The French Revolutionary Wars continued from 1799 with the French fighting the forces of the Second Coalition . Napoleon Bonaparte had returned from Egypt and taken control of the French government . He prepared a new campaign , sending Moreau to the Rhine frontier and personally going to take command in the Alps , where French forces had been driven almost out of Italy in 1799 . At the start of the campaigning season of 1800 , the Austrians had strong armies North and South of the Alps The French had Both the Austrians and the French decided to make their main effort in Italy . ( Bonaparte would have preferred the main attack to be on Kray by a flanking move through Northern Switzerland , but the working relationship with Moreau was poor ) . Italy . Melas attacked first , and by the third week in April had advanced to the Var , with Massena and half his army in Genoa besieged by land by the Austrians and under tight blockade by the Royal Navy . In response Berthier moved – not to the threatened frontier , but to Geneva - and Massena was instructed to hold Genoa until 4 June . The Army of the Reserve was joined by Napoleon , and in mid - May set out to cross the Alps to attack the Austrian rear . The bulk of the army crossed by the Great St . Bernard Pass , still under snow , and by 24 May 40 , 000 troops were in the valley of the Po . Artillery was manhandled over with great effort and ingenuity ; however an Austrian - held fort on the Italian side ( although bypassed by infantry and cavalry ) prevented most of the artillery reaching the plains of Northern Italy until the start of June . Once over the Alps , Napoleon did not proceed directly to the relief of Genoa . Instead , he advanced on Milan , to improve his lines of communication ( via the Simplon and St Gotthard passes ) and to threaten Melas ' s lines of communication with Mantua and Vienna , in the belief that this would cause Melas to raise the siege of Genoa . He entered Milan on 2 June and by crossing to the South bank of the Po completely cut Melas ' s communications . Taking up a strong defensive position at Stradella , he confidently awaited an attempt by the Austrian Army to fight its way out . However , Melas had not raised the siege of Genoa , and on 4 June , Massena had duly capitulated . Napoleon then faced the possibility that , thanks to the British command of the Mediterranean , far from falling back , the Austrians could instead take Genoa as their new base and be supplied by sea . His defensive posture would not prevent this ; he had to find and attack the Austrians before they could regroup . He therefore advanced from Stradella towards Alessandria , where Melas was , apparently doing nothing . Convinced that Melas was about to retreat , Napoleon sent strong detachments to block Melas ' s routes northwards to the Po , and southwards to Genoa . At this point , Melas attacked , and for all the brilliance of the previous campaign , Napoleon found himself at a significant disadvantage in the consequent Battle of Marengo ( 14 June ) . Napoleon was effectively defeated in a tough battle in the morning and early afternoon ; Melas , thinking he had already won , had turned over delivery of the coup de grace to a subordinate , when the prompt return of a detached French force under Desaix and a vigorous French counter - attack ( in the course of which Desaix was killed ) converted the battle into an important French victory . Melas promptly entered into negotiations which led to the Austrians evacuating Northern Italy west of the Ticino , and suspending military operations in Italy . Napoleon returned to Paris after the victory , leaving Brune to consolidate in Italy and begin a march toward Austria . Germany . In May and June , Moreau invaded across the Southern part of the Rhine with 100 , 000 men , converging on Bavaria . Gen . Kray ' s Austrians were completely outflanked and beaten at Stockach , Engen , Messkirch and Biberach , being forced to take refuge in Ulm . A long armistice followed , after which Kray was replaced by the Archduke John , with the Austrian army retiring behind the river Inn . When the armistice ended , John advanced over the Inn towards Munich and Moreau defeated the Austrians overwhelmingly in the forests before the city at Battle of Hohenlinden on 3 December . Moreau began a march on Vienna , and the Austrians soon sued for peace , ending the war on the continent . Egypt . Meanwhile , Kléber remained trapped in Egypt by the British fleet . He negotiated the Convention of El - Arish with Britain and Turkey to allow him to evacuate by sea , but Britain later repudiated the agreement . Kléber won a battle against the Turks at Heliopolis in March , but was assassinated later in June .