Third Treaty of San Ildefonso

The Third Treaty of San Ildefonso was a treaty between France and Spain in which Spain returned the colonial territory of Louisiana to France. The treaty was concluded on 1 October 1800 between Louis Alexandre Berthier representing France and Don Mariano Luis de Urquijo for Spain. The treaty was negotiated under some duress, as Spain was under pressure from Napoleon, although Spain did gain the Tuscany area. The terms of the treaty did not specify the boundaries of the territory being returned, which later became a point of contention between Spain and the United States after the Louisiana Purchase in 1803, in which France sold its territory to the United States. This treaty also affirmed the earlier Treaty of Alliance signed at San Ildefonso on 19 August 1796.

The French Revolution ended in Napoleon's taking of executive and legislative power in his coup of 18 Brumaire on 9 November 1799, whilst France was immersed in the War of the Second Coalition.

Following the signature of the Peace of Basel, which put an end to the War of the Pyrenees between France and Spain, both countries maintained a military alliance embodied in the signing of the Second Treaty of San Ildefonso on 1796, which committed either party to go to war against a third country if attacked. It was this alliance that led to Spain's entry into the war against Great Britain, leading to the loss of Trinidad and Menorca in 1798 and the attacks on Ferrol and Cadiz in 1800. Spain's financial system was facing serious trouble; from 1780, banknotes were circulating as legal currency, as a new form of government bonds invented by Francisco Cabarrús. The British attacks on Spain's colonies and convoys returning from America, along with Britain's commercial blockade, added to an already worsening economic situation, with the national debt increasing eightfold between 1793 and 1798.Charles IV and Maria Luisa of Parma ruled Spain, with Manuel Godoy as prime minister.

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