Spain knew toward the end of the seventeenth century that her enemy France soon would be colonizing the Mississippi valley. Wilderness guarded Mexico (New Spain) from an attack by any French soldiers who should garrison the future posts of Louisiana. In order that a hostile fleet might not sail against Spanish ports of the Gulf, Spain took steps to occupy the one still unoccupied Gulf port deep enough to serve as base for such a fleet. 1 So in April of 1693 a Mexican mathematician, Don Carlos de Siguenza y Gongora, led an official expedition into Pensacola bay to investigate that harbor and its possibilities.
"Spanish Fortifications of Pensacola, 1698-1763,"
Florida Historical Quarterly: Vol. 20
, Article 4.
Available at: https://stars.library.ucf.edu/fhq/vol20/iss2/4