28 June to 29 July On 24 June 1709, the Allied force feigned an attack on Ypres and successfully forced Villars to re-manoeuvre his army. The allies then turned towards Tournai. By noon of 27 June, most of Marlborough's British and Dutch soldiers were in position outside the city.
Prince Eugène's force arrived at Tournai that evening and the following morning. As Marlborough and Eugène's forces marched on Tournai the
Prince of Orange was tasked with capturing
Mortange and
Saint-Amand, to safeguard the siege operations against French attacks from the side of
Valenciennes. The primary objective was Fort l'Escarpe, which controlled the crossing of the Scheldt. Orange was fortunate when, after only a dozen shots from his accompanying field guns, the drawbridge unexpectedly fell without being destroyed. Taking advantage of this, his troops swiftly stormed the fort, met little resistance, and captured the garrison. On the night of 28 to 29 June, Prince Eugène ordered the construction of bridges over the swampy ground surrounding the Tournai to enable communication between Allied positions on both banks of the Scheldt river. It was decided that Marlborough would conduct the siege while Eugène commanded the covering force. The Allied soldiers started to dig trenches around Tournai on 30 June. The siege corps, under the
chief in situ Marlborough, consisted of 60 infantry battalions and 70 cavalry squadrons. The Allied force was mainly made up of British, Austrian, Prussian and Dutch soldiers, with smaller numbers of Danish, Hessian and Hanoverian troops. In response to the Allied arrival outside the city, Surville had all of the
water locks blocked, causing the river to accumulate in such a way that made getting between the two banks of the Scheldt nearly impossible. Nonetheless, by 4–6 July the Allied forces had surrounded the city with trenches and the garrison of Tournai was denied any communication with the outside. Marlborough was eager to end the siege as quickly as possible. On the night of 8 to 9 July, the Allies conducted simultaneous attacks on three sections of the fortifications. The first and largest was commanded by
Lieutenant-General Lottum, the second by
Lieutenant-General Fagel and the third by
General Schulenburg. The besieging troops made it to within 200-300 paces of the counterscarp, but heavy rain delayed further work. On 10 July, elements of Lieutenant-General Bettendorf's Allied siege artillery finally reached Tournai. The French sallied out with 500 men, but the Spanish regiment in the vanguard deserted and the remainder of the force returned to the city. By 11 July, the remainder of the siege artillery had arrived at Tournai. Overall, 100 heavy guns and 60 mortars had been transported by ship from
Ghent. However, due to the heavy rain, the Allied trenches were filled with water and the artillery pieces could not be put in position. The shelling of Tournai finally began on 13 July and within a week the besiegers managed to drive the French out of their entrenchments in front of the citadel. On the night of 20 to 21 July, the French attempted a
sortie near the Valenciennes Gate. The effort was repulsed, but the French succeeded in disrupting Allied siege works. The following night, a similar French sally was repulsed. On the night of 26 July, Allied troops captured the sluice and important outer-works on all three approaches. On 28 July, Eugène and Marlborough inspected the siege works, while a French sortie employing 200 men was repulsed. Surville held a council of war where it was decided to surrender the city and to retreat to the citadel with what was left of the garrison (approximately 4–5,000 out of 7,700 French soldiers). On 29 July, Surville surrendered the city of Tournai.
30 July to 3 September On 30 July, Surville retired to the citadel with his remaining 4–5,000 men on the condition that, if he was not relieved by 5 September, the citadel would be handed over to the Allies. The Allies entered the city through the Lille Gate and occupied it with 10 battalions. In the meantime a temporary
armistice was agreed between the parties, while Surville sent the Marquis de Ravignan to
Versailles to obtain orders from Louis XIV. On the advice of Surville, the French king refused to consider the capitulation of the citadel and ordered the French garrison to continue to resist. Instead, Louis offered a ceasefire on the Flanders front. This was rejected by Marlborough. Shortly after the surrender of the city, Marlborough relocated his camp to
Orchies, 19km south-west of Tournai, so that he could better monitor the movements of Villars' army. He left command of the siege to his Prussian and Dutch officers. On 1 August, Prussian
Lieutenant-General Lottum proceeded with the siege of the citadel. The citadel was described by the British soldier John Marshall Deane as "an invincible strong place for mines". On 8 August,
Lieutenant-General von Schulenburg opened a second front of attack, but the coordination between Lottum and Schulenburg was poor. Allied casualties were high, even in the final days of the siege. Mining and countermining became a particular feature of the fight for the citadel, often involving subterranean engagements in terrible conditions. On 26 August, the French blew up a mine which killed more than 400 men. On 27 August, a French attempt to sally from the citadel was betrayed by deserters and repelled by German infantry. With food supplies running low, on 31 August, Surville offered to surrender to Marlborough, but the Allied commanders rejected his proposals. On 1 September, the Allies resumed the shelling of the citadel. In response, Surville threatened that if the garrison had to surrender as
prisoners of war, he would blow up the bastions. On 3 September, the Duke of Marlborough finally accepted Surville's conditions of surrender. The siege had lasted 69 days. The French garrison, now numbering no more than 2,400 men, left the citadel with the
honours of war and returned to France as part of a prisoner exchange. ==Aftermath==