The French generals, aware how much the fortress was straitened, were meanwhile straining every nerve to raise the siege; but such was the terror inspired by Marlborough's presence, and the skill with which his defensive measures were taken, that they did not venture to hazard an attack on the covering army. But a well-conceived project of Vendôme's, for throwing a supply of powder into the fortress, in part succeeded; although many of the horsemen who carried it were cut off, some succeeded in making their way in through the Allied lines, and considerably raised the spirits of the garrison, as well as prolonged their means of defence. But meanwhile the ammunition of the besiegers was falling short, as well as that of the besieged; and as the enemy were completely masters of the communication with Brussels, no resource remained but to get it up from Ostend. A convoy was formed there accordingly by General Erle, and set out on the 27th September, consisting of seven hundred waggons, escorted by General Webb with ten thousand men. Count de la Motte instantly set out with the troops under his command from the vicinity of Ghent, and came up with the convoy in the defile of Wynandals. A sharp action ensued, and the French advanced to the attack with their wonted impetuosity. But Webb's defensive arrangements were so skilful, and the fire kept up by his troops so vigorous, that the enemy were utterly routed; and the convoy forcing its way, reached Menin on the following day, and entered the Allied camp, amidst the acclamations of the whole army, on the 30th September.[35]
The safe arrival of this convoy gave new energy to the operations of the siege; while the recovery of Eugene relieved Marlborough of half the labour under which, to use his own words, he had been for a fortnight "rather dead than alive." Three days after the whole tenaillon was carried, and the troops established directly opposite the breaches of the ramparts. Meanwhile Vendôme opened the sluices, and inundated the country to the very borders of the dyke, so as to intercept Marlborough's communication with Ostend, and prevent the arrival of stores from it. But the English general defeated this device by bringing the stores up in flat-bottomed boats from Ostend to Leffinghen, and thence conveying them in carriages, mounted on very high wheels, to the camp. Cadogan greatly distinguished himself in this difficult service. Overkirk died at this critical juncture, to the great regret of Marlborough, who could then ill spare his ardent and patriotic spirit. Meanwhile, however, the siege continued to advance, and fifty-five heavy guns thundered from the counterscarp on the breaches, while thirty-six mortars swept all the works which commanded them. Finding himself unable to withstand the assault which was now hourly expected, Boufflers, on the 22d October, beat a parley, and capitulated; having sustained, with unparalleled resolution, a siege of sixty days, of which thirty were with open trenches. Penetrated with admiration at his gallant defence, Eugene granted the French general and his brave garrison the most honourable terms. The gates were surrendered on the 23d, and the remainder of the garrison, still five thousand strong, retired into the citadel,[36] where they prolonged their defence for six weeks more.