In an instant the cannon of the fort roared out, the bells clanged the alarm, blue fires were lighted, and the dead silence was succeeded by a perfect chaos of sounds.
The party under the bridge waited quietly, until the noise as of a large body of men coming upon the bridge from the town end was heard.

At the first outbreak Gerald Dillon had, with some difficulty, lit first some tinder, and then a slow match, from a flint and steel--all of these articles having been most carefully kept dry during the trip, with the two pistols, which were intended to fire the fuses, should the flint and steel fail to produce a light.
As the sound of the reinforcements coming on to the bridge was heard, Gerald Dillon on one side, Rupert Holliday on the other, left the log, and swam with a slow match in hand to the boats.

In another instant the fuses were lighted, and the three companions swam steadily downstream.
In twenty seconds a loud explosion was heard, followed almost instantaneously by another, and the swimmers knew that their object had been successful, that two of the boats forming the bridge would sink immediately, and that, the connexion being thus broken, no reinforcements from the town could reach the garrison of the Fort Saint Michael.

Loud shouts were heard upon the bridge as the swimmers struck steadily down stream, while the roar of the musketry from Fort Saint Michael was unremitting.
Half an hour later the three adventurers landed, at a point where a lantern had, according to arrangement, been placed at the water's edge by Pat Dillon, who was in waiting with their clothes, and who received them with an enthusiastic welcome.

Five minutes later they were on their way back to their camp.
In the meantime the battle had raged fiercely round Fort Saint Michael.