Florida passed to British control in 1763 with the signing of the Treaty of Paris. A Royal Proclamation on October 7 of that year established West Florida as a colony and Pensacola was designated as its capital.
Haarmann, Albert W.
"The Spanish Conquest of British West Florida, 1779-1781,"
Florida Historical Quarterly: Vol. 39
, Article 2.
Available at: https://stars.library.ucf.edu/fhq/vol39/iss2/2