Commodore Edward Preble had assumed command of the U.S. Mediterranean Squadron in 1803. By October of that year Preble had begun a blockade of Tripoli harbor. The first significant action of the blockade came on 31 October when the USS Philadelphia ran aground on an uncharted coral reef and the Tripolitan Navy was able to capture the ship along with its crew and Captain William Bainbridge. The Philadelphia was turned against the Americans and anchored in the harbor as a gun battery.