In 1803 he got his first command, the little schooner Enterprise, which he exchanged, after a short time, with Decatur, who brought out from America the Argus, a handsome sixteen-gun brig, lately off the stocks. In the Argus he took an active part in the bombardment of Tripoli, and manifested his usual steadiness and coolness. Commodore Preble, wishing to examine the harbor as closely as practicable during the bombardment, trusted to Hull's seamanship to get him the best view possible, and reconnoitred one night in the Argus. It came near being the end of the vessel and all on board, by one of those accidents against which skill and courage avail nothing. A heavy shot struck the brig's bottom, and raked it for several feet, ripping the plank out as it went. Had it gone an inch deeper, the ship's bottom would have been out; but the gallant brig and her brave company were saved for great services to their country. After the reduction of the Barbary powers Hull returned home, and in 1806 he reached the rank of post-captain. He was then thirty-one years old, short and stocky, but military in his bearing, prompt and decided in his manner, kind to his men, but a firm disciplinarian. He was singularly chivalrous to women, and treated the humblest woman with the highest respect. In 1811 Hull got the Constitution, and with her, Lieutenant, afterward Commodore, Charles Morris, a lieutenant worthy of such a captain. In the celebrated chase of the Constitution the following year, scarcely less praise is due to Morris, then her first lieutenant, than to Hull. The Constitution's first duty was to take a large amount of specie to Holland, in payment of interest on a debt due by the United States. From thence she proceeded to Portsmouth, England.