Towards late spring the increased activity of the besiegers caused a corresponding restiveness among the many prisoners within the city. Sir Guy Carleton had treated them with as much liberality as was possible under the circumstances; but on an attempt on the part of some of the officers to bribe the guard, he speedily placed the offenders in irons. On the last day of March a large number of prisoners made an attempt to escape from the Dauphin barracks, just inside St. John's Gate. Their plan was to overpower the guard, whose strength was necessarily small, capture the adjacent city gate, and hold it open for their comrades on the Plains. The plot was discovered, however, and the prisoners were transferred to the British gunboats in the harbour. As the weeks went by, the anxiety of an ever threatened attack told heavily on the garrison, and even the convalescent were called upon for guard-house duty. A blockade extending over four or five months was exhausting their provisions; and for fuel they were at length reduced to tearing down wooden houses in the suburb of St. Roch. For half a year the Richelieu, Montreal, and Three Rivers, in fact the whole of Canada, had been virtually in the enemy's hands; Quebec alone remained, but, commanded by Carleton, Quebec was a fortress in the most real sense. It was the evening of the 3rd of May, and in the gathering darkness a ship rounded Point Lévi and drew near to the ships in the basin. Cheers rose from the garrison and a saluting gun boomed from the citadel. Still the strange craft made no salute, and a heavy crash of artillery burst from the Grand Battery. For answer, flames leaped up the rigging and along the bulwarks of the approaching schooner. It was the _Gaspé_, which the enemy had fitted up as a fire-ship and sent into the harbour. The crew, being disconcerted by the alert challenge of the garrison, hastily lighted the fuses and escaped in small boats, but only to see the impotent fire-ship carried down the river by the ebbing tide. Meanwhile, the invading army had drawn near to the ramparts, intending to assault the town under the confusion caused by the _Gaspé_. To these dogged troops, steeled for their last great effort, the failure of the fire-ship was a severe blow. Moreover, their slight remaining hope vanished a day or two later when the British frigate _Surprise_, arrived in the harbour, having boldly forced its way through the ice-packs which still beset the lower river. Not long afterwards the _Isis_, fifty guns, and the sloop-of-war _Martin_ also rounded Point Lévi. After six months of toil, privation, and suspense the brave garrison was at last relieved. Once more in Quebec numberless joy-bells rang out, and artillery crashed triumphantly across the tide. Flags ran up on every bastion and parapet within the walls, and the cheers of the reinforced garrison carried dark despair to the enemy's camp across the Plains.