The capture of Fort Bute signalled the opening of Spanish intervention in the American Revolutionary War on the side of France and (nominally) the United States. Mustering an ad hoc army of Spanish regulars, Acadian militia, and native levies under Gilbert Antoine de St. Maxent, Louisiana Governor Bernardo de Gálvez stormed and captured the small British frontier post on Bayou Manchac on September 7, 1779.
Charles III of Spain had declared war on Britain on July 21, and Gálvez had prepared accordingly with singular efficiency. On August 15, a vicious hurricane swept over Gálvez' base in New Orleans, sinking his fleet, destroying his provisions, and bringing to ruin every existing military plan. Undeterred, Gálvez rallied the support of the colony and by August 27 had set out on the land route toward the British West Florida territory.
The Spaniards reached Fort Bute at the end of a murderous eleven-day march that reduced their army by several hundred. The shocked British garrison, unaware that war had been declared, surrendered without a fight.