Northern edge of the Espinoza-Sanchez cattle station
In 1736, tensions in Europe between Britain and Spain were getting worse by the month in a feud that had already lasted three decades. In that same year, Don Diego de Espinosa established his cattle station on Diego Plains, now known as Palm Valley. As primary provider of food to the Spanish colonial capital of St. Augustine, his ranch was a vital asset. British colonies north of the St. Marys River already vociferously objected to the trade policies of their Spanish colonial neighbor to the south and when the Spanish coast guard seized a British merchant vessel in the West Indies, the War of Jenkins Ear was the result.
In anticipation of British retaliation (and to stave off attacks by renegades), the Espinoza compound was quickly fortified by the Spanish governor of East Florida. He authorized the erection of a 15-foot high palisade with two bastions at opposite corners. Manned by a regular garrison of 16 Spanish soldiers, the post became known as Fort San Diego (Fuerte de San Diego). The fort was armed with nine swivel guns, five two-pound Falconetes cannon and an assortment of small arms. On May 23, 1740, during the British invasion of St. Augustine, General James Oglethorpe's 400 man army attacked the fort but found it doubly defended by 32 regular troops, along with workers totaling 50 men. Nevertheless, British forces did eventually capture the fort, adding a ditch and earthworks. They occupied the fort only long enough to protect the St. Johns River to St. Augustine supply line. They dismantled and evacuated the fort on July 25 but the site was reclaimed soon after by the Spanish. Three years later, the British returned with several hundred indian allies and totally destroyed Fort San Diego, killing as many as 40 Spanish troops in the process. It would take another two decades before hosilities ceased in East Florida and by then most landowners in the Diego Plains were nearly ruined.
Southern edge of the Espinoza-Sanchez cattle station
Espinoza's daughter married into another of the area's more prominent families in 1756. Her new husband, Joseph Sanchez, would prove to be a shrewd businessman. Not only was he successful in renewing the title to the Sanchez and Espinosa land holdings from the new Spanish governor, but merged the two enormous grants into a single plantation that eventually spread over 1,000 acres. The property would remain in the extended family until well after 1790. During the territorial period however, ownership of the estate began to splinter. By the time the centennial of Florida's statehood had arrived, the fort and its history had been all but forgotten.
Somewhere behind this house is buried the actual fort
In 1918, a resident of Palm Valley found a half-buried cast iron cannon in the woods about a quarter of a mile east of Palm Valley Road. Archaeologist William Jones later identified it as one of the 30 inch, carriage mounted "Falconetes" from the fort, captured by General Oglethorpe. A short distance from where the cannon was found, several small round shot were also unearthed. The William Jones report on Fort Diego, published in 1993, is still one of the best resources for detailed information on the site.