Marshal Suchet had received Orders from Napoleon to commence operations on the 14th of June; and by rapid marches to secure the mountain Passes in the Valais and in Savoy, and close them against the Austrians. On the 15th, his troops advanced at all points for the purpose of gaining the frontier from Montmeilian, as far as Geneva; which he invested. Thence he purposed to obtain possession of the important Passes of Meillerie and St Maurice; and in this way to check the advance of the Austrian Columns from the Valais. At Meillerie the French were met and driven back by the Advanced Guard of the Austrian Right Column, on the 21st of June. By means of forced marches the whole of this Column, which Baron Frimont himself accompanied, reached the Arve on the 27th of June.
The Left Column, under Count Bubna, crossed Mount Cenis on the 24th and 25th of June. On the 28th, it was sharply opposed by the French at Conflans; of which place, however, the Austrians succeeded in gaining possession.
In order to secure the passage of the Arve the Advanced Guard of the Right Column detached, on the 27th, to Bonneville, on its left; but the French, who had already fortified this place, maintained a stout resistance. In the mean time, however, the Austrians gained possession of the passage at Carrouge; by which means the French were placed under the necessity of evacuating Bonneville, and abandoning the Valley of the Arve. The Column now passed Geneva, and drove the Enemy from the Heights of Grand Saconex and from St Genix. On the 29th, this part of the Army moved towards the Jura; and, on the 1st July, it made its dispositions for attacking the redoubts and intrenchments which the French had thrown up to defend the Passes. The most vigorous assault was made upon the Pass of Les Rousses; but the Austrians were driven back. Reserves were then brought up; and the French having quitted their intrenchments to meet the latter, and a good opportunity having offered for a flank attack upon them with Cavalry and Artillery, the Pass was captured by the Austrians: and the French were compelled to abandon both it and the other Passes of the Jura. The Austrian Advanced Guard pursued the Enemy, and reached, in the evening, St Claude, on the road leading to the left from Gex; and St Laurent, in the original direction of the attack, beyond Les Rousses.
In the mean time, the Austrian Reserve Corps, under Lieutenant Field Marshal Meerville, was directed to advance, and to throw back the French upon the Rhone. The latter, in retreating, destroyed the Bridge of Seyselle; and, by holding the Fort of l'Ecluse, closed the road from Geneva to Lyons. A redoubt had been constructed in front of the Fort, and completely commanded the approach. It was gallantly stormed and carried by the Regiment of Esterhazy. The Fort itself was now turned by the Reserve Corps along the left bank of the Rhone, with the design of forcing the passage at the Perte du Rhone. Here the French had constructed a tête de pont; which, however, they were forced to abandon in consequence of a movement made by the First Corps under Lieutenant Field Marshal Radivojevich. On retiring, they destroyed the very beautiful stone bridge then existing; and thus rendered it necessary for the Austrians to construct temporary bridges over the extremely narrow space between the rocks which confine the stream at this remarkable spot. The Advanced Guard of the Reserve Corps, under General Count Hardegg, first crossed the Rhone, and found the Enemy posted at Charix, in rear of Chatillon, on the road to Nantua. Count Hardegg immediately attacked him; and, after encountering an obstinate resistance, forced him to retire.
The troops of the First Austrian Corps, which, in the mean time, were left in front of the Fort l'Ecluse, had commenced a bombardment; and this, after twenty six hours' duration, considerably damaged the Fort. A powder magazine exploded, which caused a general conflagration; to escape which the garrison rushed out, and surrendered at discretion to the Austrians: and thus, in three days, the high road from Geneva to Lyons was opened to the Army of Italy.
On the 3rd July, General Bogdan, with the Advanced Guard of the First Austrian Corps, having been reinforced by Lieutenant Field Marshal Radivojevich, attacked the Enemy with much impetuosity at Ojanax, beyond St Claude; where the French General Maransin had taken up a favourable position, with 2,000 men. The Austrians turned his Left Flank, and forced him to retire. The Corps reached Bourg en Bresse on the 9th July.
On the 10th July, a Detachment, under Major General von Pflüger, was pushed on to Maçon on the Saône; and gained possession of the tête de pont constructed there, and of the place itself.
On the 7th July, the Second Corps, under Count Bubna, reached Echelles. A Detachment, consisting principally of Sardinian troops, under Lieutenant General Count Latour, had been directed to observe Grenoble; in front of which its Advanced Guard arrived on the 4th July. On the 6th, the suburbs were attacked; and the communication between this place and Lyons was cut off. The garrison, consisting of eight Battalions of the National Guard, offered to capitulate on the 9th, on the condition of being permitted to return to their homes. That a vigorous defence might have been maintained was evident from the fact of the Austrians having found in the place fifty four guns and eight mortars, and large quantities of provisions.
Count Bubna's Corps and the Reserve Corps, by simultaneous movements, assembled together in front of Lyons on the 9th. An Armistice was solicited by the garrison on the 11th July, and granted upon condition that Lyons and the Intrenched Camp should be evacuated; and that Marshal Suchet should retire with his Corps behind the Loire, keeping his Advanced Posts within a stipulated line of demarcation.
Having secured possession of the line of the Rhone as far down as its junction with the Isère, as also of that part of the Saône between Maçon and Lyons; the Army of Italy now proceeded towards the upper line of the latter river, leaving the Second Corps, under Count Bubna, at Lyons, in front of Marshal Suchet. The First Corps marched upon Chalons sur Saône, in order to gain the tête de pont at that point. At this time, the Fourth Division of the Army, under the French General Lecourbe, was at Salins, between Dôle and Pontarlier: and as Besançon had not yet been invested, Baron Frimont detached a part of the Reserve Corps, under General Hecht, to Salins; whilst General Fölseis, detached from the First Corps towards Dôle. The Advanced Guard of the First Corps had arrived in front of the tête de pont at Chalons, and had completed its dispositions for attack; when the place surrendered. By the advance, at the same time, of Hecht upon Salins, and of Fölseis from Dôle upon Besançon; the retreat of the French General Laplane was completely cut off. This led to a Convention which stipulated the dissolution of the National Guards, the surrender of all the Officers, and the abandonment of one of the Forts of Salins to the Austrians.