As part of the treaty that ended the French-Indian War in America, which also occurred during the Seven Years War involving a number of countries, Spain ceded the territory of Florida to Great Britain in exchange for Spain obtaining the Louisiana territory. At the time, Florida’s panhandle extended west to the Mississippi River which included the city of Baton Rouge. British troops quickly moved into the fort at Baton Rouge. British Lieutenant Alexander Dickson was given charge over protecting Great Britain’s western Florida border along the Mississippi. This included Baton Rouge, Fort Bute (on Bayou Manchac about 115 miles north of New Orleans) and Fort Panmure (modern day Natchez, Mississippi).
On May 8, 1779, Spain’s King Charles III officially sided with the American colonies in their war against Great Britain.
On July 8, 1779, King Charles III issued a declaration authorizing Spanish subjects in the American colonies to take up hostile actions against the British.
On July 21, 1779, Bernardo de Gálvez received notification of King Charles III’s orders allowing him to fight the British. Gálvez was the Spanish Governor of Louisiana and a military officer of Spanish troops in Louisiana. Upon receiving the news, Gálvez immediately began planning his strategy against the British in West Florida, starting with the fort at Baton Rouge.
On August 27, 1779, Gálvez set off with a force of 520, consisting of mostly Spanish regulars along with 60 American militiamen, 80 free blacks and mulattoes and 10 American volunteers led by Oliver Pollock. Their destination was Baton Rouge. Before reaching their first target – Fort Bute – the Spanish force numbered over 1,000 with the addition of American Indians and Acadians (French and French descendants who settled in the area).
On September 7, 1779, Gálvez reached Fort Bute and launched his attack. Dickson had only left a small contingent of British and some German troops at the fort and they proved no match for the Spanish invaders. One German was killed and the rest surrendered, except 6 who escaped to Baton Rouge to warn them of the advancing Spanish force.
On this day, September 21, 1779, Gálvez and his force reached Baton Rouge where Dickson and his British troops were located. The Spanish had managed to dig trenches within musket range of the garrison at Baton Rouge and began using their artillery to shell the British. After only 3 hours of bombardment by the Spanish, Dickson surrendered Baton Rouge to Gálvez.
Gálvez was a shred strategist and demanded that Dickson not only surrender Baton Rouge, but also Fort Panmure and all of the British regulars stationed there. Dickson realized he had no alternative and agreed to the terms of surrender.
This removed the last British placements along the Mississippi River, allowing unobstructed access up the river for both the Spanish and American colonists. They now had free sailing all the way north to the Ohio Valley which greatly helped their supply lines in the fight against the British in the Revolutionary War.
Sources for the above includes: Today in Florida History – Spaniards capture Baton Rouge; Battle of Baton Rouge in (West Florida) Louisiana Begins; The Battle of Baton Rouge – The American Revolution in Louisiana; Spaniards Capture Baton Rouge; Louisiana’s Fight in the Revolutionary War; Battle of Baton Rouge (1779) – Baton Rouge, Louisiana;