By the time Galzev obtained the commission that led to his fame, a colonel leading Spanish forces in Louisiana, he had fought wars and led troops at sea and on several continents. The Spanish Crown selected Galvez as the new governor of Louisiana, and on January 1, he took command of the colony at the age of thirty-one. At that time, the colony was home to eight thousand colonists of European descent, an equally large number of enslaved people of African descent, two hundred free people of African descent, and a large but unknown number of Native Americans.
Utilizing local militias that combined men of African, Acadian, Native American, and European descent, as well as a small force of professional soldiers, Galvez led numerous attacks against British positions that forced the British onto the defensive. Galvez's army forced the British to withdraw from Baton Rouge and Natchez. With a thousand men under his lead, he also captured a British fort at Mobile. By 1781, his force had grown to eight thousand and he accepted the surrender of a substantial British force at Pensacola.
Following his successful campaigns against the British in the American Revolution, Galvez led attacks on British positions in Jamaica and the Bahamas. He died from a disease he contracted while in the Caribbean in 1786.