 Construction of Fort De Soto, on Mullet Key facing the mouth of Tampa Bay, was begun in 1898 during the Spanish–American War to protect Tampa Bay from potential invading forces.The fort, a subpost of Fort Dade on adjacent Egmont Key (which lies in the mouth of Tampa Bay), was equipped with artillery and mortar batteries.Even into the early years of the 20th century, West Hillsborough had no paved roads, and transportation posed a major challenge.