Maria I of Portugal 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 September 29, 1801 John VI signed the Treaty of Madrid (1801), ceding half of Guyana to France, which became French Guiana. The refusal of the Portuguese government to join the French-sponsored Continental Blockade against Britain culminated in the late 1807 Franco-Spanish invasion of Portugal led by General Junot. The ultimate Napoleonic plan for Portugal was to split it into three sections. The northern parts of Portugal,
Japan–Russia border into the Soviet Union in 1945. Russia treats the islands as an integral part of the country. There are no border crossing points on the Russian-Japanese border, as it is a purely maritime boundary. During the existence of the land border in Sakhalin (1905-1945), it was crossed by one road. Soviet–Japanese border conflicts Japan–Russia border The Japan–Russia border is the "de facto" maritime boundary that separates the territorial waters of the two countries. According to the Russia border agency, the border's length is 194.3 km. The two countries do not share a terrestrial border, although in 1905-1945 the Russian Empire,