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.



The First Barbary War (1801–1805), also known as the Tripolitan War and the Barbary Coast War, was the first of two Barbary Wars, in which the United States and Sweden fought against the four North African states known collectively as the "Barbary States".The cause of the U.S. participation was pirates from the Barbary States seizing American merchant ships and holding the crews for ransom, demanding the U.S. pay tribute to the Barbary rulers. United States President Thomas Jefferson refused to pay this tribute. Sweden had been at war with the Tripolitans since 1800.