The combats on the Var of 13-28 May 1800 marked the high point of Austrian success during the fighting in Italy in 1800, and saw an Austrian force under Melas and Elsnitz attempt to destroy Suchet's left wing of the French Army of Italy.
At the start of April the French line had run along the Italian coast to Genoa, but in early April Melas broke the French lines, isolating Massena in Genoa. Suchet, with the left wing of the Army of Italy, was slowly forced back along the coast, suffering defeats at Borghetto (2 May 1800) and Oneglia (7 May 1800) and losing control of the Col de Tende (6 or 7 May 1800). The French were forced to retreat back across the Var River, just to the west of Nice, reaching their new positions on 11 May.
Once over the river Suchet reorganised his army. Clausel's division (Seras's and Brunet's brigades) held the bridgehead at Saint-Laurent-du-Var on the coast. Rochambeau's division (Solignac and Jablonowsky) held the line of the Var up to La Broc (eight miles to the north). Ménard was posted at Le Broc (Lesuire and Delaunay). Garmier's division was next in line, and stretched from La Broc up to Malaussène, where the Var valley turned west. Thurreau's division then took over, and held a line eighteen miles long back to Entrevaux.
Suchet's only hope of preventing an Anglo-Austrian invasion of Provence was that Napoleon and the Army of Reserve would enter Italy early enough to force Melas to return to the Italian plains before the thin French line was overwhelmed (the British element would have come from the Royal Navy, which had warships cruising off the coast).
At first the Austrian army on the Var was commanded by Melas. His line ran from the sea up to Aspremont, with outposts further north. By mid May Melas was starting to receive the first reports of Napoleon's advance, but at this point he refused to believe them. As the news became more certain Melas was faced with a dilemma. If he withdrew all of his forces from the Var then Suchet would be able to advance to Genoa and lift the siege, but if he left too many troops on the coast then Napoleon might be able to defeat his main army around Turin.
Melas decided that the best way to deal with the problem would be to defeat Suchet, removing one threat. Elsnitz made the first attack on the French bridgehead on 13 May, but this failed. Melas believed this was because of a lack of artillery, which had to be brought by sea to Nice. On 22 May the heavy guns were ready, and Melas ordered a second assault. Lattermann's and Bellegarde's grenadiers advanced in three columns towards the French bridgehead, supported by the artillery and by fire from British frigates anchored in the mouth of the Var. They were allowed to advance to within half-pistol shot range of the fortification, before the French opened fire with grapeshot and musket fire. After suffering heavy losses the Austrians were forced to retreat.
By this point Melas could no longer doubt that Napoleon was in Italy, and left the coast to return to Turin. He was still unwilling to pull Elsnitz off the Var, but his orders now were to avoid any serious fighting, and if necessary retreat to the line of the Roya.
Elsnitz ignored these orders, and on 27 May made another attack on the French lines. By now Suchet had been reinforced, and he was ready for the attack. The Austrian artillery bombardment began at three in the evening, when twenty heavy cannon opened fire. The attack itself began at ten. Once again the French allowed the Austrians to get close to their lines before opening fire, and once again the Austrians were forced back with heavy casualties. A second attack was made an hour later, but this also failed.
On 27 May the French returned to the offensive. Garnier's division attacked the Austrian positions on the Vésubie River, which flows into the Var close to La Broc. The Austrians were pushed out of Saint-Jean-la-Rivière, and out of a village identified in early French sources at Ronciglione. Gorupp was forced to retreat up the valley to Belvédère secure his line of retreat via the Col de Rauss, which links the Var and Roya valleys.
On 28 May Menard's division attacked Ulm's and Saint-Julien's brigades, which made up Elsnitz's centre at Aspremont, while Clausel attacked from the bridgehead at Saint-Laurent. Elsnitz decided not to stand and fight, and began to retreat back towards Italy.
The heavy guns were re-embarked on the ships, and taken to Livorno. Most of the other guns were sent up the Col de Tende, while the main army, with 10-12 light guns, retreated to the heights of La Turbie (overlooking Monaco).
Suchet followed, sending Clausel along the coast towards Monaco, with the reserve half a day's march behind. Rochambeau was sent across the mountains to Sospel, on the approaches to the Col de Tende. The French left was moved to Duranus, in the Vésubie valley, and then east to Luceram, on the way to Sospel.
On 31 May Melas finally ordered Elsnitz to retreat back towards Turin. The direct route was across the Col de Tende, the pass that linked Nice to Cuneo, but the French cut this route (combat of Breglio, 1-2 June 1800), and Elsnitz was forced to retreat back across the mountains, reaching Ceva on 6 June.