Fort Matanzas National Monument preserves Fort Matanzas, a small Spanish coquina watchtower built between 1740 and 1742 on the Matanzas River to guard the southern approach to St. Augustine through Matanzas Inlet. Constructed under Gov. Manuel de Montiano after James Oglethorpe exploited the inlet during his 1740 siege of St. Augustine, the fort was manned by a tiny garrison but armed to control the channel. In 1742 it repelled scouting boats from Oglethorpe’s returning force, the only time it fired on an enemy. Later neglected after shifts in control of Florida, it had fallen into ruin by 1821 and was restored in the 20th century.