The siege of Bellegarde of 6 May-17 September 1794 saw the French recapture this important border fortification in the eastern Pyrenees over a year after it had fallen to the Spanish. Although it had been the French who declared war in 1793 (War of the Convention), it was the Spanish who went onto the offensive, advancing across the mountains in April 1793. At first Bellegarde was only masked, but in May a full blockade was put in place, and on 25 June the fortress fell to the Spanish.
For the next year the fighting took place on the French side of the mountains, but on 30 April-1 May the Spanish were pushed out of their camp at Le Boulou and were forced into a chaotic retreat back across the Pyrenees. A garrison of 8,000 men, commanded by the Marquis de Val-Santaro, was left in Bellegarde, while most of the Spanish army reformed under the guns of Figueres.
General Dugommier, then the commander of the French Army of the Eastern Pyrenees, decided to conduct a blockade of Bellegarde, aware that any attempt to storm the fortress would be very costly. The Marquis de Pérignon, with 15,000-20,000 men was left to conduct the blockade, while the rest of the army formed a covering force on the southern slopes of the mountains.
The Spanish commander, General La Union, made a number of attempts to break the blockade, starting with an unsuccessful attack on the right of the French army covering the siege on 19 May. In June he attempted to distract the French with attacks on their extreme right, in the Cerdanya, but these also failed. Finally, in mid-August La Union decided to make another attack on the French covering forces, but this too failed (battle of San Lorenzo, 13 August).
While La Union was attempting to raise the siege an epidemic was sweeping through the garrison. By 31 July it had been reduced to a quarter of its full size. The Marquis of Val-Santaro held on for a month after the Spanish failure on 13 August, but eventually, on 17 September, he was forced to surrender.
When the French occupied the fortress they discovered 68 guns and 40 thousand barrels of gunpowder, confirming just how expensive a storm would have been. When the news of the capture of Bellegarde reached Paris the Convention renamed it "Sud-Libre" (Freedom South), to match the fortress of Condé, which was renamed "Nord-Libre".