Forces sent by Yusuf Karamanli of Tripoli to retake Derna from the Americans attack the city.
The Battle of Derna at Derna, Cyrenaica, was the decisive victory in AprilMay 1805 of a mercenary army recruited and led by United States Marines under the command of U.S. Army Lieutenant William Eaton, diplomatic Consul to Tripoli, and U.S. Marine Corps First Lieutenant Presley Neville O'Bannon. The battle involved a forced 521-mile (839-km) march through the North African desert from Alexandria, Egypt, to the eastern port city of Derna, Libya, which was defended by a much larger force.
Yusuf (ibn Ali) Karamanli, Caramanli or Qaramanli or al-Qaramanli (most commonly Yusuf Karamanli), (1766 – 1838) was the longest-reigning Pasha of the Karamanli dynasty of Tripolitania (in present-day Libya). He is noted for his role in the Barbary Wars against the United States.