War of the Oranges
In 1801 Spanish Prime Minister Manuel de Godoy sent an army to invade Portugal with backing from Napoleon, resulting in the War of the Oranges. Though the Spanish ended their invasion, the Treaty of Badajoz on 6 June 1801 forced Portugal to cede Olivença and other border towns to Spain. (This cession is not recognized by the present Portuguese government, and the country officially considers those territories still to be Portuguese possessions.) On 29 September 1801 John VI signed the Treaty of Madrid (1801), ceding half of Portuguese Guyana to France, which became French Guiana.