Combined British, Portuguese and colonial Brazilian forces begin the Invasion of Cayenne during the Napoleonic Wars.

The Portuguese conquest of French Guiana, also known as Conquest of Cayenne, was a military operation against Cayenne, capital of the South American colony of French Guiana, launched in January 1809 in the context of the Napoleonic Wars. The invasion was undertaken by a combined expeditionary force that included Portuguese and British military contingents.

The Napoleonic Wars (1803–1815) were a global series of conflicts fought by a fluctuating array of European coalitions against the French First Republic (1803–1804) under the First Consul followed by the First French Empire (1804–1815) under the Emperor of the French, Napoleon Bonaparte. The wars originated in political forces arising from the French Revolution (1789–1799) and from the French Revolutionary Wars (1792–1802) and produced a period of French domination over Continental Europe. The wars are categorised as seven conflicts, five named after the coalitions that fought Napoleon, plus two named for their respective theatres: the War of the Third Coalition, War of the Fourth Coalition, War of the Fifth Coalition, War of the Sixth Coalition, War of the Seventh Coalition, the Peninsular War, and the French invasion of Russia.

January 6 is the sixth day of the year in the Gregorian calendar; 359 days remain until the end of the year.