The battle of Montebello (20 May 1859) was the first major clash between French and Austrian forces during the Second War of Italian Unification and saw a French division force part of the Austrian IX Corps to retreat.
At the start of the war the Piedmontese were badly outnumbered by the Austrians, and had to hold out until their French allies could arrive in strength. The Austrians missed this chance for a quick victory, and by 12 May, when Napoleon III arrived at Genoa, the French had arrived in strength. The Allied armies were based around Alessandria, from where they could threaten the left flank of any Austrian advance on Turin or could threaten the Austrian right and rear by advancing along the southern side of the Po.
After a brief thrust towards Turin the Austrian commander, Feldzeugmeister Franz Count Gyulai, decided to withdraw into the area between the Sesia and the Ticinio Rivers. At first he moved into a line that ran from the northwest at Vercelli, through Mortara and on south-east to the Po, but in mid May, as the strength of the French army became more apparent, he moved again. VII Korps was posted at Vercelli on the Austrian right. II and III Korps were at Mortara, V Korps was between Mortara and Pavia and VIII Korps was at Pavia. The Austrian line now ran from west to east and faced south. General Urban's IX Korps also arrived in theatre, and was posted at Piacenza, east of the main Austrian position.
The French didn’t make any significant moves for a week after Napoleon's arrival. After a week Baraguey d'Hilliers' I Corps was moved east along the south bank of the Po, first to Tortona and then to Voghera. While most of the corps stopped there General Forey's division pushed on to the east, heading for the village of Montebello.
At the same time the Austrians had decided to carry out a reconnaissance in force in the same area. Two brigades from Urban's Korps and three from Stadion's V Korps were involved, but this strong force was split into three columns and a reserve. Only Urban's column would be involved in the main fighting at Montebello and the Austrians would be actually outnumbered during most of the fighting.
The battle would be fought at the northern edge of the Apennine Mountains. Montebello and the nearby village of Genestrello were built on spurs that jutted out from the mountains into the flat plains of the Po, which ran away to the north. Urban's two brigades were moving west along the main road from Stradella to Casteggio, which ran along the edge of the plains. The other two columns were further to the north and north-west.
The Piedmontese cavalry played a major role in the Allied success. At around 11.30am a squadron from the Novara Regiment spotted Urban's advance guard while it was still at Casteggio. Soon afterwards the Aosta regiment found the Austrian central column, under General Paumgartten, about four miles to the north. The three cavalry regiments then managed to keep both Paumgartten and the Prinz von Hessen's right column away from the main fighting. Forey would only have to deal with Urban's two brigades, and not all of those men would be engaged.
The Austrians reached Montebello at around 1.30pm and decided to advance another mile to Genestrello before stopping for the day (not the most ambitious of schedules!). Forey had already posted his outposts in Genestrello, and so when the Austrians advanced they came under fire. A fierce battle broke out around Genestrello at about 2.30pm as both sided rushed reinforcements into the fight. Forey won that battle, eventually getting five battalions to a defendable farm house at Cascina Nouva on his left and six to Genestrello. Urban got two thirds of his men into the fight, but was outnumbered on both flanks.
The fight at Genestrello only lasted for half an hour, before the Austrians of Brigade Schaafshottsche were pushed back towards Montebello. This forced Brigade Baum to retreat from Cascina Nouva. Schaafschottsche, with some help from Gaal's brigade from the central column, threw up some defences in Montebello, and prepared to defend the village.
Forey brought up ten battalions for the attack on Montebello (around 6,000 men). This time the French were outnumbered, but they were more determined. The attack began between 4 and 5pm. The Austrians were forced back until their last foothold was in the graveyard at the northern end of the village, and by 6.30 they were forced to abandon that last position.
In the aftermath of this defeat the Austrians continued to retreat, convinced that the rest of I Corps must be close behind Forey's division. Forey was actually fighting on his own, and was thus in no position to give chase.
The Austrians suffered much heavier casualties than the Allies at Montebello, losing 331 dead, 785 wounded and 307 missing, a total of 1423. The French reported to have lost 105 dead, 549 wounded and 69 missing, a total of 723. As would happen repeatedly during the rest of the war the Austrians had thrown away their numerical superiority by splitting their army into too many detachments.
The battle of Montebello met with mixed reactions on both sides. The Austrians were worried that it signalled the start of the general Allied advance south of the Po. Gyulai reacted by moving some of his troops further to the south. However they were pleased with the actually results of the fighting, believing that they had faced the entire I Corps and not just one division.
The Allies were pleased with the victory, especially as they exaggerated the number of Austrians involved and believed that they had defeated some 30,000 men, twice the true numbers. On the other hand they had believed that Gyulai would be fairly passive, and the fighting at Montebello proved that this might not be the case. The French paused for a week while they decided what to do next. Eventually Napoleon decided to move to the north-west to attack the weakened Austrian right. This move led to the first major battle of the war, at Magenta on 4 June 1859, an Allied victory that forced the Austrians to retreat east.