(trĭpŏl'ĭtӘn), 1800–1815, conflict between the United States and the Barbary States. Piracy had become a normal source of income in the N African Barbary States long before the United States came into existence. The new republic adopted the common European practice of paying tribute to buy immunity from raids. Difficulties began in 1800 when William Bainbridge, the officer who took tribute to the dey of Algiers, was compelled to go under the Ottoman flag to Constantinople. When the pasha of Tripoli demanded (1800) more tribute than previously agreed upon, the United States refused payment.
Hostilities broke out in 1801, but Commodore Richard Dale's blockade of Tripoli failed to daunt the pirates. President Thomas Jefferson then decided to settle the affair by negotiation, but his envoy Richard Valentine Morris could not reach an agreement with the pasha. The war continued. Tunis was more or less drawn into the struggle because of ill feeling between the bey's court and William Eaton, the U.S. consul there.
After Eaton and Morris quarreled over the campaign, the blockade of Tripoli was lifted, and the U.S. government considered resuming tribute payments. Edward Preble then succeeded Morris as the U.S. commander in the Mediterranean. Preble dispatched the frigate Philadelphia under Bainbridge to resume the blockade. A storm drove the ship aground. It was captured, and Bainbridge and his crew were imprisoned. Stephen Decatur and a small group of men were sent (Feb., 1804) into the harbor. They set fire to the Philadelphia and destroyed her.
Despite this exploit Preble was still unable to take Tripoli, and, in Sept., 1804, he was succeeded by Samuel Barron. Meanwhile William Eaton had convinced the U.S. government of his plan for supporting a rival claimant for the rule of Tripoli by a land expedition. Eaton landed in Egypt and after an arduous march took the port of Derna. Before he could advance farther, the war was ended. John Rodgers, sent out with a strong force in May, 1805, negotiated a settlement in June. The U.S. prisoners were ransomed, and Tripoli renounced all rights to halt or to levy tribute on American ships.
Though the most favorable agreement yet made with a Barbary power, the treaty was not a brilliant triumph and did not end the threat of piracy to U.S. shipping. During the later Napoleonic Wars and the War of 1812, the pirates increased their raids on American commerce. Algiers actually declared war on the United States. In 1815 a squadron under Decatur forced the dey of Algiers to sign a treaty renouncing U.S. tribute, and the so-called Algerine War was ended. After 1815 the United States no longer paid tribute to any Barbary State.