The Oyapok, or Vicente Pinzon, is the best-known of the group and forms the boundary line between Brazil and French Guiana under the arbitration award of 1900.
The same principle which dictated the conquest of French Guiana originated attempts to seize the Spanish colonies of Montevideo and Buenos Aires, Portugal being also at war with Spain.
There had for a long period been difficulties with France with regard to the territory which lay between the mouth of the Amazon and Cayenne or French Guiana.
Napoleon had forced the Portuguese government to cede to him the northernmost arm of the mouth of the Amazon as the southern boundary of French Guiana with a large slice of the unexplored interior westwards.
On the 9th of February 1792, he succeeded in having a law passed sequestrating the possessions of the émigrés, and demanded, though in vain, the deportation of refractory priests to French Guiana.
