The Position in Italy
The French Plan
The Marengo campaign (May-14 June 1800) was a crucial moment in Napoleon's career, helping to secure his position as First Consul, and to restore his earlier conquests in Italy. The first year of the War of the Second Coalition saw the French expelled from most of their conquests in Italy, leaving them with control of Genoa and a coastal strip running back to France. Napoleon had used these setbacks as part of the justification for taking power as First Consul, and although the military situation had actually stabilised by the time he took power this meant that a military victory was essential if he was to remain in power.
The Position in Italy
At the start of 1800 the Austrians controlled all of the northern Italian plain, while the French held the line of the Alps and Apennines, and had a continuous line along the coast to Genoa. This all changed in early April, when Melas attacked the French line to the west of Genoa, reaching the coast and isolated Massena in Genoa. After fighting a skilful campaign in the mountains around the city Massena was forced back into Genoa, where he was trapped between a British fleet and the Austrian army. Suchet, with the left wing of the Army of Italy, was forced back towards the River Var, just across the modern French border. By late April the largest Austrian forces were on the coast - Elsnitz and Melas were on the Var, while Ott was besieging Genoa. The Austrians also had smaller forces covering Turin and Milan. Melas was planning to invade the south of France, supported by the British navy, while other Austrian troops would threaten the French position in Switzerland. The Austrians hoped that this would pull enough French troops away from the Rhine to allow Kray to go onto the offensive there.
The French Plan
French planning was complicated by Napoleon's coup of 18th Brumaire (9 November 1799). Although he had become First Consul, his position was not yet entirely secure, and he could not yet issue direct orders to some of his senior colleagues. General Moreau, commander of the Army of the Rhine, saw himself as Napoleon's equal, a situation that would force Napoleon to abandon his first plan of campaign for 1800.
This plan would have seen the main French effort come in Germany. Moreau would have moved to the right bank of the Rhine and pushed the Austrians under Kray back across the Lech. The reserve of Army of the Rhine and the Army of the Reserve would then have crossed the St. Gotthard Pass and the two French armies would have advanced towards Vienna on opposite sides of the Alps. Moreau saw this plan as an attack on his own power, as Napoleon would have been present in Germany, and also didn't believe that it was practical. To prevent Napoleon putting this plan in action Moreau spread his army out along the Rhine.
Napoleon then decided to campaign in Italy instead. At first he hoped to cross the St. Gotthard or Simplon Pass to attack deep into the Austrian rear, but in mid-April the French line on the Italian coast collapsed, isolating Genoa. There was also a chance that the Austrians might attack west across the Mount Cenis attack from Turin, and so Napoleon decided to take the newly formed Army of the Reserve across the Great St. Bernard Pass. This would bring him into Italy to the north-west of Turin, and would still allow him to get behind Melas.
Napoleon's exact objectives at the start of the campaign are still the subject of some controversy. Officially he was planning to move south to Turin, and then on to Genoa, to lift the siege. Once he was in Italy Napoleon abandoned this plan, and instead moved east to capture Milan, before attempting to cut the main Austrian supply line along the Po. What isn't clear as at what point Napoleon adopted this second plan. Some authors are convinced that this was always Napoleon's plan, and that he never had any intention of saving Massena, who was after all one of his rival for military prestige and thus power, while others believe that the change of plan came after the French had crossed the Alps and realised that Milan was poorly defended.
The Army of the Reserve began the campaign with four corps. Lannes commanded the advance guard, which contained Watrin's division and Rivaud's cavalry. Duhesme commanded a corps made up of Boudet's and Loison's divisions, and Victor commanded Monnier's, Chambarlhac's and Chabran's divisions. Finally Murat commanded the cavalry. The structure of the army would change repeatedly during the campaign, as Napoleon reacted to changing events. Another force, under Thurreau, was to cross the Mount Cenis pass from Savoy, while Moncey's division from Moreau's army would cross the St. Gotthard Pass soon after the campaign began.
Napoleon left the Tuileries on 6 May, reaching Geneva two days later. The Army of the Reserve was soon on the move, with most of it heading towards the Great St. Bernard Pass. On 16 May Napoleon left Lausanne to join the march, and on the morning of the same day Watrin's division of the advance guard reached the summit of the Great St. Bernard. After pausing briefly to receive supplies from the monks at the top of the pass they continued on down the pass, overwhelming a small Austrian detachment at Saint Remy. On the next day Lannes took the town of Aosta, and then paused to wait for Rivaud's cavalry, and for Chabran's infantry division, which had crossed the Little St. Bernard. Both arrived during the day. On 18 May Lannes advanced down the Doire Baltèe, defeating another Austrian force at Châtillon.
The French now ran into the first serious obstacle, Fort Bard, just over ten miles further down the valley. This well positioned fort blocked the main road, and effectively prevented the French from getting their artillery any further the valley. An assault on 21-22 May failed. Lannes, with the advance guard, but without artillery, then slipped past the fort on mountain paths, soon followed by most of the rest of the army. Chabran was left behind to conduct a regular siege, which ended in success on 2 June, freeing the road for the bulk of the French artillery.
Meanwhile Lannes took the advance guard south, defeating the Austrians at Ivrea (24 May) and then at Romano-Chiusella (26 May). This helped convince the Austrians that Napoleon was planning to head south past Turin towards Genoa. Given the lack of certainly about when Napoleon changed his plans, it is possible that he was still planning to head south at this point, but if so that plan was soon abandoned.
Napoleon's plan was now to advance east towards Milan, which was weakly defended. From Milan, he would then advance south-east towards the Po, cross the river and block the main Austrian supply line from Turin to Mantua. This would force Melas to advance east to attack Napoleon on ground of Napoleon's own choosing, and hopefully at time when part of the Austrian army was still occupied at Genoa. The ideal position for this planned battle would be at Stradella, half way between Piacenza and Alessandria, and a point where the Apennines came close to the marshy area close to the Po. The fall of Genoa on 4 June meant that Napoleon would be forced to modify this plan, and turn west in an attempt to defeat Melas before all of the Austrian forces to his west could be reunited. It would be during this advance west that the French would unexpectedly run into Melas's united forces just to the east of Alessandria, triggering the battle of Marengo.
By now Melas had realised that he was facing a major French offensive. He left the Var on 22 May, and reached Turin on 25 May, the day before the French victory at Romano-Chiusella. Over the next few days the Austrian position became increasingly precarious as French columns emerged from a series of Alpine passes. On 22 May Thurreau crossed the Mount Cenis pass, to the west of Turin. He was defeated at Avigliano on 24 May, but resumed his advance on 27 May. This helped to convince Melas that the main French effort was coming from the west. For some time Melas refused to believe that Napoleon had crossed the Alps, and was only convinced when his presence was reported by a cavalry officer who knew Napoleon by sight.
On 27 May the first of two columns detached from the Army of the Rhine entered the picture when General Moncey, at the head of 14,000 men, crossed the St. Gotthard Pass and captured Bellinzona. Two days later a smaller force under Bethencourt emerged from the Simplon Pass, captured Domodossola and advanced towards Arona.
The French army advanced towards Milan in two main columns. Napoleon, with the main army, advanced on the left, heading east from Ivrea to Vercelli, then to Turbigo on the Ticino River, crossing the river on 31 May. To the right Lannes remained at Chivasso on 29 May, but then advanced east, past Casale and on towards Pavia. On 2 June Napoleon entered Milan, receiving a somewhat muted reception. On the same day Lannes reached Pavia. The Austrians were now split in two. Vukassovich and Dedovich were being forced east towards Mantua, Ott was still besieging Genoa, Elsnitz had just been forced back from the Var, and was about to be forced to conduct a costly retreat across the mountains, and Melas was at Turin.
The situation was transformed on 4 June, when Massena was finally forced to surrender at Genoa. This freed Ott, with the largest part of the Austrian army, to move north to join with Melas. With no need to protect his links to Genoa, Melas would be able to bypass Napoleon's planned road-block at Stradella, either moving to the coast at Genoa or up to Milan. However the Austrians were also now threatened from the west. Ott had been forced to let the French garrison of Genoa march away, and at Finale on 7 June it joined up with Suchet's army advancing from the Var. The combined army then turned north, advancing to Dego and then onto Acqui. Further west Menard captured the Col di Tenda on 3 June, and began to threaten Cunea.
For the next few days Napoleon, unaware of the fall of Genoa, continued to carry out his plan. The French now advanced south-east from Milan, with their left wing heading for Cremona, their centre for Piacenza, and their right for Pavia and the Po at Belgiojoso. Duhesme reached Cremona on 4 June while Murat with his cavalry and Boudet's infantry reached the Po opposite Piacenze on 5 June. At the same time an Austrian column under Gottesheim was approaching Piacenza along the Trebbia valley, cominh from Genoa. Moncey and Napoleon remained at Milan, while Chabran was sent south to Pavia, with orders to march along the north bank of the Po.
On 6 June Melas left Turin with Kaim, Hadik and the Austrian cavalry, heading for Alessandria. On the same day Austrian cavalry under O'Reilly occupied Piacenza, and the Austrian reserve artillery was sent west, towards the concentration of forces at Alessandria. On 6-7 June Lannes, with the French advance guard (now the right wing), crossed the Po at Belgiojoso, and threatened to capture the reserve artillery, but O'Reilly managed to hold him off until most of the artillery was safe.
On 7 June Boudet crossed the Po east of Piacenza, and captured the city. He was then attacked by Gottesheim's advance guard, which arrived from Genoa one day too late to help defend the city. Gottesheim was forced to retreat west, joining O'Reilly. On the same day Ott advanced north-east from Gavi, towards Stradella and then on to Piacenza. This route would bring him into direct contact with Lannes, who by now had reached Napoleon's main objective, the narrow gap at Stradella.
On 8 June Napoleon, who was still at Milan, received captured dispatches that announced the fall of Genoa. This meant that Melas would no longer need to fight his way past Napoleon's roadblock at Stradella. Napoleon decided to move west in an attempt to bring on a decisive battle before the Austrians could escape, and ordered Lannes to move west from Stradella towards Voghera, and expecting that Lannes would only run into scattered outposts. Instead he found Ott's force of 12,000 men. The resulting battle of Casteggio-Montebello (9 June 1800) ended in a French victory, and Ott was forced to retreat west towards Alessandria, where on 10-11 June he joined up with Melas and Elsnitz. Unknown to Napoleon the main Austrian army was now concentrated at Alessandria.
Napoleon's own army was now also concentrated, around Voghera, just over twenty miles to the east. Melas now took advantage of a double-agent, François Toli, who partially convinced Napoleon that the Austrians were planning to break out to the north, cross the Po at Casale and head for Pavia and Milan. In fact Melas was planning to attack to the east, along the main road to Mantua. This ruse convinced Napoleon to split his army. On 13 June Desaix's corps (Boudet and Monnier) was sent south towards Novi (on the road from Alessandria to Novi), to watch for Austrian forces believed to be approaching from Genoa, while Lapoype was sent north to watch for any Austrian attempt to escape across the Po. That evening Victor took Marengo village and Pedrabona farm, and came close to the Bormida River. This French success came close to disrupting the Austrian plans for the following day, but it also helped convince Napoleon that he was facing the Austrian rearguard and not the main army, and thus helped to prepare for the Austrian successes on the next day.
The battle of Marengo began with a series of Austrian attacks on the French positions. By early afternoon the French were falling back, and by four the battle appeared to be lost. Only the late arrival of Desaix, who had been summoned back from Novi earlier in the day, restored the situation. These reinforcements allowed the French to launch an unexpected counter-attack on the advancing Austrians, and a near-certain defeat was turned into a crushing victory.
On the day after the battle Melas sent envoys to Napoleon asking for an armistice, and by the end of the day the two men had signed the armistice of Alessandria. This saw the Austrians retreat behind the Mincio, while the French occupied the area west of the Chiesa. The area between the two rivers was to remain neutral. The terms of this agreement were ratified by Francis II, and on 26 June Napoleon was free to return to Paris to secure his political power.
Although Marengo was a decisive victory within the Italian theatre, it didn't end the war. Fighting resumed late in 1800, before Moreau's victory at Hohenlinden on 3 December 1800 exposed Vienna to attack, and convinced the Emperor Francis II to make peace.