Signing of Third Treaty of San Ildefonso

Date: October 1, 1800 • Location: Furnas County, United States

With the signing of the Third Treaty of San Ildefonso, Spain returned the colonial territory of Louisiana to France in return for territories in the Italian region of Tuscany.

The Third Treaty of San Ildefonso was a secret agreement signed on 1 October 1800 between Spain and the French Republic by which Spain agreed in principle to exchange its North American colony of Louisiana for territories in Tuscany. The terms were later confirmed by the March 1801 Treaty of Aranjuez.