The first fort built by Europeans on Tampa Bay was not Fort De Soto, and it did not end well. In 1567, more than three centuries before the United States poured a single yard of the mortar battery's concrete, the Spanish admiral Pedro Menendez de Aviles raised a small wooden fort at the capital town of the Tocobaga and left about thirty soldiers to hold it. Within a year every one of them was dead. That vanished garrison is the dark first chapter of the bay's military history, and the truest measure of how completely Fort De Soto's story inverts it.
Fresh from founding St. Augustine in 1565 and slaughtering the French Protestants who had dared to settle Florida, Pedro Menendez de Aviles spent the late 1560s trying to bind the peninsula's powerful Native chiefdoms to Spain through a chain of coastal forts and Jesuit missions. He had already planted garrisons among the Calusa to the south and along the Atlantic coast, and in early 1567 his effort brought him into Tampa Bay. He came at a delicate moment: the Tocobaga and the Calusa were at war, and the Calusa king the Spanish called Carlos, Menendez's uneasy ally, wanted the Spanish to help him crush his northern rivals. Instead Menendez sailed up to the principal town of the Tocobaga, on the bay's northern shore near present-day Safety Harbor, and brokered a peace between the two enemies, a piece of diplomacy that pleased neither side and quietly poisoned his standing with the Calusa.
To make the new arrangement permanent, Menendez did what a sixteenth-century Spanish commander did: he built a fort in the middle of the Tocobaga capital and left armed men in it. The fort was a modest wooden blockhouse, and the garrison numbered around thirty soldiers, planted in the heart of a populous and proud chiefdom that had not asked for them, hundreds of miles by sea from the nearest Spanish help at St. Augustine. With the soldiers came the work of the Jesuit mission that Menendez had brought to Florida under Father Juan Rogel and Brother Francisco Villarreal, for the garrison's purpose was not only military but spiritual: to hold the Tocobaga to the Spanish alliance and to convert them to the Catholic faith. It was an impossible assignment, sustained only by the chief's tolerance, and that tolerance did not last.
The position collapsed the way such occupations almost always did, over food, over Spanish demands, over the fundamental insult of an armed foreign garrison in a people's own capital. Relations curdled into hostility through 1567, and by about January 1568, within a year of the fort's founding, the Tocobaga rose and destroyed it, killing the entire garrison. Spain's bid to hold Tampa Bay collapsed with the blockhouse. The wider Jesuit effort in Florida was failing at the same time, expelled, killed, or abandoned chiefdom by chiefdom, and within a few years the Jesuits gave up on Florida altogether. The Spanish would never again seriously fortify Tampa Bay. The Tocobaga town went on without them; the fort left almost no physical trace, and even its exact location is lost.
The 1567 garrison matters most for the frame it gives the whole archive. Six separate times across three and a half centuries, soldiers and surveyors looked at this bay and concluded it needed a fort: Menendez in 1567, the Spanish pilots Franco and Celi in the 1750s, George Gauld in 1765, Robert E. Lee's engineer board in 1849, and finally the builders of Fort De Soto in 1898. The very first of those forts was overrun and its garrison killed to the last man, three hundred and thirty-one years before the last one was begun. And the last, Fort De Soto, never fired a shot in anger and was abandoned without ever facing an enemy. Between annihilation and irrelevance lies the entire strange military history of Tampa Bay, and the 1567 garrison is where it begins.