The First Barbary War (1801–1805), also known as the Tripolitanian War and the Barbary Coast War, is the first of two Barbary Wars between the United States and the four North African Muslim states known collectively as the "Barbary States".

Three of these are nominal provinces of the Ottoman Empire, but in practice autonomous: Tripoli, Algiers, and Tunis.

The fourth is the independent Sultanate of Morocco.

The cause of the war is 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 refuses to pay this tribute.