Probably Brock received then Sir George Prevost’s letter of August 2 warning him of the intended armistice, for Hull repeatedly and earnestly asserted that Brock spoke to him of the armistice August 16; and although twelve days was a short time for an express to pass between Montreal and Malden, yet it might have been accomplished at the speed of about fifty miles a day. If Brock had reason to expect an armistice, the wish to secure for his province the certainty of future safety must have added a motive for hot haste. At noon August 15 Brock sent a summons of surrender across the river to Hull. “The force at my disposal,” he wrote, “authorizes me to require of you the surrender of Detroit. It is far from my inclination to join in a war of extermination, but you must be aware that the numerous body of Indians who have attached themselves to my troops will be beyond my control the moment the contest commences.” The threat of massacre or Indian captivity struck Hull’s most sensitive chord. After some delay he replied, refusing to surrender, and then sent orders recalling McArthur’s detachment; but the more he thought of his situation the more certain he became that the last chance of escape had vanished. In a few days or weeks want of provisions would oblige him to capitulate, and the bloodshed that would intervene could serve no possible purpose. Brock’s movements increased the general’s weakness. As soon as Hull’s reply reached the British lines, two British armed vessels--the “Queen Charlotte” of seventeen guns and the “Hunter” of ten guns--moved up the river near Sandwich, while a battery of guns and mortars opened fire from the Canadian shore and continued firing irregularly all night on the town and fort. The fire was returned, but no energetic measures were taken to prepare either for an assault or a siege.