U.S. Army officer and adventurer who in 1804 led an expedition across the Libyan Desert during the so-called Tripolitan War.

After service in the U.S. Army, Eaton was appointed consul at Tunis (1798) by President John Adams. In 1803 he won President Thomas Jefferson's approval for a plan to settle U.S. maritime differences with Tripoli by removing its government and reinstating the exiled Pasha Hamet Karamanli. Eaton marched from Egypt westward, with 10 U.S. marines, a number of Arabs, and Karamanli. With the help of a U.S. naval bombardment, he took Derna (Darnah; April 27, 1805), but when the ruling pasha at Tripoli agreed to a treaty with the United States, Eaton was obliged to curtail his operation. Afterward he returned to the United States.