In March 1796 Napoleon was appointed to command the French army in Italy. His mission was to invade northern Italy and occupy Lombardy with the aim of forcing the Austrian troops to move south from the Rhine where the principal offensive was expected to take place. Conceived as a diversionary campaign, it in fact worked to bring an end to the War of the First Coalition and establish Napoleon’s reputation as a military commander.
Having crossed the Apennines, Napoleon’s first victory was at the Battle of Montenotte, where he succeeded in dividing the Piedmontese army from their Austrian allies. After a further conclusive French victory on 23 April, General Colli of the Piedmontese army was forced to sue for peace. Napoleon went on to engage the Austrian army in a series of battles. After victory at the Battle of Lodi on 10 May, he entered Milan triumphant. He then embarked on the siege of Mantua, before beginning a campaign in the Papal States. On 19 May Pope Pius VI sued for peace, agreeing to pay a large indemnity and allow French troops to occupy Bologna and Ferrara. In late July, however, the Austrians sent a fresh army to confront Napoleon and lift the siege of Mantua. At the Battle of Castiglione on 5 August, the French were able to bring greater numbers to bear against the Austrians and, after initial setbacks, they resumed their siege.
In early 1797 the Austrians launched a final relief effort. Defeats, however, at the Battles of Rivoli and La Favorita were decisive. Mantua capitulated on 2 February and, at the Treaty of Tolentino, the Pope agreed to cede Bologna, Ferrara and Ancona to the French. Having conquered most of northern Italy, Napoleon then set out to invade Austria. The court of Vienna appointed Archduke Charles to command the Austrian forces against Napoleon. They were, however, defeated at the Battle of Tagliamento, and the French subsequently forced their way across the Isona. Napoleon’s advance created panic in Vienna as the court prepared to evacuate the city. As a result, peace negotiations began at Leoben and continued for several months. The Treaty of Leoben was a preliminary accord signed on 17 April 1797 which stipulated that Austria would lose the Austrian Netherlands and Lombardy in exchange for the Venetian territories of Istria and Dalmatia. The agreement was ratified on 17 October 1797 by the Treaty of Campo Formio, which effectively brought an end to the War of the First Coalition. It marked a resounding success for Napoleon, who had begun the Italian campaign as a young, and relatively unknown, commander.