The siege of Lille of 29 September-7 October 1792 was the main Austrian contribution to the Allied invasion of France at the start of the War of the First Coalition, but ended in failure after news of the French victory at Valmy (20 September) forced the Austrians to retreat. The attack on Lille was commanded by Duke Albert of Saxe-Teschen, the husband of Archduchess Maria Christina, the staathalter or governor of the Austrian Netherlands. Sources differ on the size of the besieging army, with figures ranging from 15,000 to 25,000, but given that the duke only had 11,600 infantry and 2,170 cavalry at Jemappes on 6 November the lower figures are more probable.
The small garrison of Lille, commanded by General Rualt (later one of officers who later accompanied Dumouriez into exile), was determined to hold out, and the siege would become famous for the courage of the citizens of the city. Lille was strongly fortified, and time was short, so rather than conduct a regular siege Saxe-Teschen decided to carry out a day-and-night bombardment of the city, hoping to force the garrison to surrender. This bombardment began on 29 September, after the duke had summoned the city to surrender, and lasted for a week. During that time 200 houses were destroyed, but the city still held out.
On 20 September the main Prussian-Austrian army invading France clashed with the French at Valmy, and failed to press home any serious attacks. At the end of September the Duke of Brunswick, commander of the army, was forced to begin a retreat back to the French border, leaving General Dumouriez free to move north to relieve the siege of Lille. A number of reinforcements under General Lamartillière had managed to enter the city during the siege, and after the Allied retreat Dumouriez sent a detachment under General Beurnonville towards Lille. A third French force, under General Labourdonnais, was also approaching from Soissons.
On 7 October Saxe-Teschen was forced to lift the siege, and retreat into the Austrian Netherlands, which was soon the target of a French invasion. Saxe-Teschen withdrew to the Cuesmes ridge, blocking the road to Brussels. On 6 November the Austrian position was attacked by Dumouriez (battle of Jemappes), and Saxe-Teschen was forced to retreat, leaving the French free to occupy the Austrian Netherlands.