1803 naval battle between the United States and the Tripoli Eyalet

1803 treaty between the United States and Native Americans

Louisiana Purchase — 1803 acquisition by the U.S. of France's claim to the territory of Louisiana

1803 marked the opening shots of the Blockade of Saint-Domingue

1803 treaty between the United States and the Kaskaskia

1803 treaty between the United States and Choctaw

1803 battle of the Second Anglo-Maratha War

1803 battle of the Second Anglo-Maratha War

1803 major battle of the Second War of Haitian Independence

1803 battle of the Second Anglo-Maratha War

1803 treaty between Great Britain and Maratha