Frederick II of Prussia was again isolated. No help was to be expected from France, whose efforts at the time were centred on the Flanders campaign. Indeed, on 31 March 1745, before Frederick took the field, Louis XV and the Marshal of France Maurice de Saxe, commanding an army of 95,000 men, the largest force in the war, had marched down the Scheldt valley and besieged Tournay. Tournay was defended by a Dutch garrison of 7,000 soldiers. In May 1745, a British army under the command of the Duke of Cumberland attempted to break the French siege and relieve Tournay. Maurice  had very good intelligence and knew the road that Cumberland was using to attack his forces besieging forces. Thus, Maurice could select the battlefield. Maurice chose to attack the British allied army on a plain on the east side of the Scheldt river about two miles southeast of Tournay near the town of Fontenoy. There the Battle of Fontenoy was fought on 11 May 1745. Fighting began at 5:00 AM with a French artillery barrage of the British-Allied forces, who were still attempting to move into their proper positions for their anticipated attack on Tournay. By noon, Cumberland's troops had ground to a halt and discipline had begun to dissolve. The British-Allied army sought cover in a retreat. It was a victory for the French that captured the attention of Europe because it overturned the mystique of British military superiority, and it pointed out the importance of artillery. On 20 June 1745, after the Battle on Fontenoy, the fortress of Tournay surrendered to the French.. How many days passed between the beginning of the Battle of Fontenoy and Tournay's surrender to the French?