This claim was enlarged as several explorers (most notably Pánfilo Narváez and Hernando de Soto) landed near Tampa Bay in the mid-1500s and wandered as far north as the Appalachian Mountains and as far west as Texas in largely unsuccessful searches for gold.

Several Native American groups (including the Timucua, Calusa, Tequesta, Apalachee, Tocobaga, and the Ais people) had been long-established residents of Florida, and most resisted Spanish incursions onto their land.

However, conflict with Spanish expeditions, raids by the Carolina colonists and their native allies, and (especially) diseases brought from Europe resulted in a drastic decline in the population of all the indigenous peoples of Florida, and large swaths of the peninsula were mostly uninhabited by the early 1700s.

Great Britain temporarily gained control of Florida beginning in 1763 as a result of the Anglo-Spanish War when the British captured Havana, the principal port of Spain's New World colonies.

As with earlier American incursions into Florida, Spain protested this invasion but could not defend its territory, and instead opened diplomatic negotiations seeking a peaceful transfer of land.

[22] After briefly exploring the area around their landing site, the expedition returned to their ships and sailed south to map the coast, encountering the Gulf Stream along the way.

However, the peoples he met (likely the Timucua, Tequesta, and Calusa) were mostly hostile at first contact and knew a few Castilian words, lending credence to the idea that they had already been visited by Spanish raiders.

Sometime in the period from 1514 to 1516, Pedro de Salazar led an officially sanctioned raid which enslaved as many as 500 Indians along the Atlantic coast of the present-day southeastern United States.

Quejo, with the backing of Lucas Vázquez de Ayllón, returned to the region in 1525, stopping at several locations between Amelia Island and the Chesapeake Bay.

On May 30, 1539, de Soto and his companions landed in Tampa Bay, where they found Juan Ortiz, who had been captured by the local Indians a decade earlier when he was sent ashore from a ship searching for Narváez.

Ortiz passed on the Indian reports of riches, including gold, to be found in Apalachee, and de Soto set off with 550 soldiers, 200 horses, and a few priests and friars.

In 1559, Tristán de Luna y Arellano left Mexico with 500 soldiers and 1,000 civilians on a mission to establish colonies at Ochuse (Pensacola Bay) and Santa Elena (Port Royal Sound).

[28]: 196–199  Two years later, René Goulaine de Laudonnière, Ribault's lieutenant on the previous voyage, set out to found a haven for Protestant Huguenot colonists in Florida.

[28]: 199–200 At the same time, in response to French activities, King Philip II of Spain appointed Pedro Menéndez de Avilés Adelantado of Florida, with a commission to drive non-Spanish adventurers from all of the land from Newfoundland to St. Joseph Bay (on the north coast of the Gulf of Mexico).

[29] Menéndez de Avilés reached Florida at the same time as Ribault in 1565, and established a base at San Agustín (St. Augustine in English), the oldest continuously inhabited European-established settlement in what is now the continental United States.

[34] In the eighteenth century, a free black population began to grow in St. Augustine, as Spanish Florida granted freedom to enslaved people fleeing the Thirteen Colonies.

[36] In 1586, English privateer Francis Drake plundered and burned St. Augustine, including a fortification that was under construction, while returning from raiding Santo Domingo and Cartagena in the Caribbean.

[42] Ybarra (Ibarra) in 1605 sent Álvaro Mexía, a cartographer, on a mission further South to meet and develop diplomatic ties with the Ais Indian nation, and to make a map of the region.

Moore, in 1704, made a series of raids into the Apalachee Province of Florida, looting and destroying most of the remaining Spanish missions and killing or enslaving most of the Indian population.

[45] Some Spanish men married or had unions with Pensacola, Creek, or African women, both slave and free, and their descendants created a mixed-race population of mestizos and mulattos.

In 1693,[46] King Charles II of Spain issued a royal proclamation freeing all slaves who fled to Spanish Florida and accepted conversion and baptism.

At the end of the war the Peace of Paris (1783) treaties (between the Kingdoms of Great Britain and Spain) ceded all of East and West Florida to Spanish control, though without specifying the boundaries.

Spain, beset with independence movements in its other colonies, could not settle or adequately govern Florida by the turn of the 19th century, with real control limited to the immediate vicinity of St. Augustine, Pensacola, and a few small towns and forts scattered across the north of the territory.

[62]American slaveholders sought to reclaim who they considered their property and organized increasingly frequent raiding parties that entered Spanish territory to attack Seminole villages and capture anyone who might be a refugee from slavery.

[63] Several local insurrections and filibuster campaigns against Spanish rule flared, some with quiet support from the U.S. government, most notably the Patriot War of East Florida of 1810–1812 led by George Mathews.

The officer commanding the Royal Navy flotilla had been made, by Captain General Juan Ruiz de Apodaca, to promise not to land in Florida without being requested to do so.

[74] Nicolls and about 150 Royal Marines were observed to disembark at Pensacola on August 26, at the request of Manrique, fearful of an attack, based upon a letter to Jackson dated September 2.

[77] The newly appointed commander of the Pensacola garrison, Francisco San Maxent, made a formal complaint to Manrique on December 31 that his men have no rations, and with due respect asks him what he should communicate to his officers.

There, Nicolls regrouped at Prospect Bluff, and rallied Indians and refugee ex-slaves living free in Florida, recruiting the latter into his detached unit of the Corps of Colonial Marines.

Southern plantation owners considered the presence of a group of armed fugitive slaves, even in a remote and sparsely-populated area of Spanish Florida, an unacceptable danger.