In this story, when and how is the narrator eventually saved?

In Edgar Allan Poe's story, the narrator saves himself by his ingenuity twice, but both times he is placed in a more torturous and deadly position after he outwits his captors. First he avoids falling into the pit because he has carefully and rationally carried out an exploration of his cell despite the pitch darkness. His exploration keeps him at the perimeter of the cell rather than in the interior. Only an accidental fall makes him aware of the pit at all, and once he knows it is there, he avoids it. Then his captors drug him, and he wakes on a low table under the swinging pendulum. When he uses his wits to entice the rats to gnaw through his bonds, he then finds the pendulum drawn up but the walls beginning to heat up and close in on him, driving him inexorably toward the rat-infested pit. At this point, there seems to be no way that he can use his intelligence to save himself. Just as he is "totter[ing] on the brink" of the pit, he hears trumpets, shouts, and a thunderous grating as the walls pull back away from the pit. Swooning, he is caught by the arms of General Lasalle, the French leader whose army has just overcome the Inquisition by seizing Toledo. If it were not for the forces of Napoleon, the narrator would have died at the hands of the Spanish Inquisition.