April 27, 1805 - US Marines along with a mercenary army begin the Battle of Derna. In 1804, the former American consul to Tunis, William Eaton, returned to the Mediterranean with the backing of the government for an ambitious plan to overthrow the ruler of Tripoli, Yusuf Karamanli. Receiving naval support from Commodore Samuel Barron, Eaton landed at Alexandria with eight US Marines under the command of First Lieutenant Presley O'Bannon. Making contact with Yusuf's deposed brother Hamet, Eaton convinced him to aid in building a mercenary army to reclaim his throne. Assembling around 500 Christian and Muslim mercenaries, Eaton and O'Bannon began marching for the Tripolitan port of Derna. They were supported during the trek by USS Argus, USS Hornet, and USS Nautilus under the command of Master Commandant Isaac Hull. After an arduous march, they reached Derna on April 27. Dividing his command, Eaton sent Hamet to the southwest to cut the road to Tripoli, while he led his group in capturing the harbor defenses. Supported by naval gunfire from Hull's ships, Eaton's force succeeded in taking the city, with O'Bannon hoisting the US flag over the harbor forts. Digging in, Eaton's men repelled a counterattack by Yusuf's army on May 13. Eager to press on to Tripoli, Eaton was thwarted when Yusuf signed a peace agreement with US Consul Tobias Lear. The victory at Derna inspired the line "To the shores of Tripoli" in the Marine Corps Hymn.

Photograph Courtesy of the US Marine Corps