At dawn on the morning of July 11, 1804, political antagonists and personal enemies Alexander Hamilton and Aaron Burr met on the heights of Weehawken, New Jersey, to settle their longstanding differences with a duel. The participants fired their pistols in close succession. Burr’s shot met its target immediately, fatally wounding Hamilton and leading to his death the following day. Burr escaped unharmed. This tragically extreme incident reflected the depth of animosity aroused by the first emergence of the nation’s political party system.

Both men were political leaders in New York: Burr, a prominent Republican, and Hamilton, leader of the opposing Federalist Party. Burr had found himself the brunt of Hamilton’s political maneuvering on several occasions, including the unusual presidential election of 1800, in which vice-presidential candidate Burr almost defeated his running mate, presidential candidate Thomas Jefferson. In 1804, Hamilton opposed Burr’s closely fought bid for governor of New York. On the heels of this narrow defeat, Burr challenged Hamilton to a duel on the grounds that Hamilton had publicly maligned his character.

Once sanctioned by law and custom, dueling declined in the Northern states after the American Revolution, though it flourished longer in the American South. By 1804, it had been outlawed in New York, forcing Burr in the aftermath of his encounter with Hamilton to give up his political ambitions and flee the state to avoid a warrant for his arrest.

Discredited by the duel with Hamilton, Burr sought to regain political power by a filibustering adventure, which led instead to his indictment for treason. He was accused of leading an expedition to create an independent nation along the Mississippi River by separating territories from the United States and Spain. With Chief Justice John Marshall sitting as circuit judge, Burr was tried for treason in federal court in Richmond, Virginia, in 1807, although he was eventually acquitted. On June 13, 1807, a subpoena was served on Thomas Jefferson to testify at Burr’s treason trial.