In June, 1779, Spain declared war on Great Britain, and Bernardo de Gálvez, then governor of Spanish Louisiana, decided to launch a preemptive attack against a likely British offensive. Having gathered all that was needed, from ships to cannons to men, he felt equipped to start his campaign by early August. Yet, in a single night, a violent hurricane over the waters of New Orleans destroyed everything Gálvez had so painstakingly prepared. It could not destroy, however, the governor’s determination to carry out the king’s orders.

On August 27, 1779, Gálvez was ready for action once more. He set out from New Orleans at the head of a colorful army: 170 veteran soldiers from the Príncipe Regiment, the España Regiment, and the Fijo de La Habana Regiment, 330 recruits from the La Luisiana Regiment, 80 militiamen from New Orleans, 80 freed African Americans, and another 600 American volunteers of every strain and status: Acadians, Germans, and French. The troops also included 160 American Indians from the Opelousa and Atakapa tribes, as well as Indians from Point Coupee and eight additional American volunteers, among them Oliver Pollock and Captain Pickles, for a total of some 1,500 men. They were the first multiracial army in North America, and according to Pollock, they marched under the flag of Spain and the new flag of the United States.

The army had ten cannons, which they transported on gunboats up the Mississippi from New Orleans, while the column of men marched determinedly toward the English posts upriver. For Gálvez, there was no time to lose if he were to take the enemy posts before news of the declaration of war between Spain and Great Britain reached them.

Eleven days after they had departed New Orleans, and about a hundred miles north of the bay, Gálvez’s troops arrived at the outskirts of Manchac. It had been an arduous journey, and a considerable number of the men, exhausted by the trek, the heat, or disease, were in no condition to fight. It was at this moment that Gálvez chose to tell his troops that Spain had declared war against Great Britain. The men responded with enthusiastic cheers. At daybreak on September 7, Gálvez led a surprise attack on Fort Manchac, capturing some twenty British redcoats. His troops continued their advance toward Baton Rouge, where they arrived on September 12 with only half the initial force. Before them was an armed stockade surrounded by a moat; it was guarded by some 400 British and German soldiers, 13 cannons, and more than 150 white and African American militiamen.

It would have taken several weeks of traditional warfare to overpower the British stronghold, so Gálvez devised a different strategy. On the night of September 20, he ordered that a battery be installed and that it immediately open fire on the British as a diversionary tactic; another battery was being positioned with the fort at closer range, while the enemy focused on the farther target. The next morning, the onslaught of unexpected short-range shots forced the enemy to surrender within three hours of battle. Gálvez’s troops captured 375 British soldiers and Waldeck allies, under the command of Lieutenant Colonel Alexander Dickinson, as well as several regimental flags, including the flag of the 16th Regiment of Foot. Oliver Pollock led the negotiations of capitulation, and Gálvez insisted that the conditions include the surrender of 80 additional soldiers from Fort Panmure in Natchez. Five hundred militiamen and slaves were released, because the Spanish army did not have enough men to guard them. The entire Mississippi River was now free from British control, allowing for the transport of goods and supplies northward without peril.