The ketch "Intrepid," which had carried Decatur and his daring followers out of the harbor of Tripoli, leaving the "Philadelphia" burning behind them, was still with the fleet. This vessel was chosen, and with all possible speed was converted into an "infernal," or floating mine. "A small room, or magazine, had been planked up in the hold of the ketch, just forward of her principal mast," writes Fenimore Cooper. "Communicating with this magazine was a trunk, or tube, that led aft to another room filled with combustibles. In the planked room, or magazine, were placed one hundred barrels of gunpowder in bulk; and on the deck, immediately above the powder, were laid fifty thirteen-and-a-half-inch shells, and one hundred nine-inch shells, with a large quantity of shot, pieces of kentledge, and fragments of iron of different sorts. A train was laid in the trunk, or tube, and fuses were attached in the proper manner. In addition to this arrangement, the other small room mentioned was filled with splinters and light wood, which, besides firing the train, were to keep the enemy from boarding, as the flames would be apt to induce them to apprehend an immediate explosion."
Such was the engine of death prepared. The plan of operations was simply to put a picked crew on this floating volcano, choose a dark night, take the "infernal" into the heart of the enemy's squadron, fire it, and let the crew escape in boats as best they might.
The leadership of this desperate enterprise was intrusted to Lieut. Richard Somers. Indeed, it is probable that the idea itself originated with him, for a commanding officer would be little likely to assign a subordinate a duty so hazardous. Moreover, there existed between Decatur and Somers a generous rivalry. Each strove to surpass the other; and since Decatur's exploit with the "Philadelphia," Somers had been seeking an opportunity to win equal distinction. It is generally believed, that, having conceived the idea of the "infernal," he suggested it to Preble, and claimed for himself the right of leadership.
But ten men and one officer were to accompany Mr. Somers on his perilous trip. Yet volunteers were numerous, and only by the most inflexible decision could the importunate ones be kept back. The officer chosen was Lieut. Wadsworth of the "Constitution," and the men were chosen from that ship and from the "Nautilus."