Siege of Tournai, 1709
The winter of 1708-9 had been a severe one and France was suffering from food shortages. Louis XIV wanted to end the War of the Spanish Succession, but he would not accept the harsh terms offered by the Allies, so the war continued. In 1709 the French considered going on the offensive by taking Lille, which had been captured by the Allies the previous year (see siege of Lille) or Courtrai, but these plans had to be shelved in view of the supply problems and low morale in the French army. Instead the French commander, Marshal Villars, reinforced Tournai and Ypres and entrenched himself between Douai and Béthune.
This left the initiative with the Allies. Marlborough wanted to feint towards Ypres and then make a drive along the coast through Dunkirk and Gravelines, as he had suggested the previous year. However, Villars' defensive lines were considered too strong and so this plan was abandoned. The Allies then debated whether to attack Ypres (on Villars' left flank) or Tournai (on his right flank), eventually settling on Tournai. The Allies moved their siege train to Menin to bluff the French into thinking that Ypres was the target, inducing Villars to withdraw 3,000 men from the garrison of Tournai to reinforce Ypres. The Allies then made a quick march to the south-east and invested Tournai on 27th June.
The fortress of Tournai was considered a strong one, having been strengthened by Vauban since its capture by the French in 1667. Cut in half by the river Escaut, the town retained its medieval walls, which had been adapted for defence against artillery by a series of demi-lunes and hornworks. The ditch was flooded on the north side of the river and was protected everywhere by a strong covered way. In addition to this, there was a powerful pentagonal citadel equipped with countermines at the south-east corner of the town.
The garrison comprised 7,000 men under the command of the governor, the Marquis de Surville-Hautfois, who was an experienced commander. Tournai was made an even more formidable obstacle by the fact that Mesgrigny, the engineer who had designed the citadel, was with the garrison. The attackers numbered 40,000 men - Marlborough took command of the siege works, whilst Eugene covered the siege with his forces. The Allies opened their trenches on the night of the 7th-8th July. There were three attacks made; one against the north-west corner of the town and two in the south either side of the river. By the 14th July there were 100 guns in action against the fortifications.
Marlborough concentrated on the stretch of rampart by the Porte de Valenciennes, between the citadel and the river, and his guns began to batter a breach in the wall. The defenders however, had not been idle. Making use of the pre-dug countermines starting in the citadel, the French were able to plant a mine beneath one of the main Allied batteries, which they detonated on 18th July. On the 20th they made a sortie and were able to destroy some of the besiegers' advanced works, further slowing down the attack. On the 25th the covered way was carried by assault and a few days later the demi-lune in front of the Porte de Valenciennes was captured by the besiegers. Breaches were battered in the wall beyond and on the 28th Surville, faced the prospect of a general assault, surrendered the town. On the 31st he retreated into the citadel with the surviving garrison (4,500 men) and 300 French wounded were allowed to evacuate to Douai. Although the siege had been far from easy for the besiegers so far, the battle for the citadel was to be far tougher.
Similar in form to that of Lille, the citadel of Tournai had a continuous false bray in front of the ramparts. Although there was no second ditch, the demi-lunes were strengthened by bonnets and lunettes. In addition to all this were the countermines that lay underneath the approaches. These were pre-dug tunnels that lead outwards from the citadel. The garrison could use them as points from which to start digging more tunnels in order to detonate mines under the besiegers' batteries and trenches. As a result, the besiegers were forced to dig their own mines in order to search for and destroy the countermines. This lead to deadly battles fought with picks and shovels in the darkness beneath the trenches.
The besiegers were met with continual resistance in the form of exploding mines and sorties from the garrison. There were two attacks made against the citadel; one from the open country to the south and one along the ditch of the town fortifications to the north (see map left). With continual setbacks, the trenches crept towards the walls with agonising slowness but despite their tenacity, the besiegers lost ground. The guns set about battering three of the citadel's bastions, two on the outer side and one on the townward side. On the 31st August the breaches were deemed practicable and the French opened talks. They surrendered and marched out on 3rd September, having held out for 69 days - an impressively long resistance. They had taken 3,800 casualties and had inflicted 5,400 on the Allies, making this one of the bloodiest sieges of war.
The siege of Tournai had taken up most of the campaigning season, but the Allies still decided to try to take Mons, which led to the costly battle of Malplaquet being fought as Villars tried to prevent the fall of Mons.