The high-stakes treason trial of Aaron Burr came at an unstable time, both in Europe and in America. The American and French revolutions worried traditional European powers, Great Britain and Spain, who were determined to keep the radical new doctrine from undermining the power of their royalty. Meanwhile, Napoleon's empire-building produced sustained military conflict on the Continent. The United States seemed on the verge of a war with Spain, even as the Administration struggled to preserve neutrality. Americans west of the Alleghenies rejoiced in President Jefferson's acquisition of the Louisiana Territory, but boundary disputes and Spanish prohibitions on Louisiana residents' entry into Nueva Espana created resentment and threats of reprisal. The Viceroy of Mexico, allied generally with western Indians, sent troops to the Sabine River to protect the Spanish frontier from invasion by United States citizens. Most Westerners saw Spain as tyrannical and viewed Texas and Florida as a rightful part of the United States. Many of these same Westerners expressed a willingness to take Spanish territory by force. Meanwhile, Spain also worried about the designs of residents of its own dominion (especially Mexico), recognizing that the unprivileged masses had grown resentful of Spanish authority. In this troubled time, the end of President Jefferson's first term, Aaron Burr stepped down from the Vice Presidency, and began preparations for a military expedition that was either - depending upon whose views one solicited - treasonous or patriotic. At its core, however, the Burr Conspiracy clearly was about conquest and adventure.
Douglas O. Linder,
The Treason Trial of Aaron Burr,
Available at: https://irlaw.umkc.edu/faculty_works/869