Fortín de San Gerónimo de Boquerón is a small fort located at the mouth of the Condado Lagoon, across from the historic sector of Miramar in San Juan, Puerto Rico. It was built during the 18th century to replace a smaller battery (called El Boquerón) that stood at the easternmost end of the San Juan islet. The original Boquerón battery was used by the Spanish to defend the city of San Juan from attacks by Sir Francis Drake in 1595 and George Clifford, the third Earl of Cumberland in 1598, who managed to destroy it during his attack. San Gerónimo became part of San Juan's first line of defense, along with the Fortín San Antonio and Escambrón Fort, while the last line of defense was the formidable Castillo San Cristóbal, which guarded the city entrance proper and also defended from land attacks. Overview The San Gerónimo and San Antonio forts were pivotal in repelling the invasion by the forces of British Admiral Henry Harvey and Sir Ralph Abercromby in 1797. On April 17, 1797, their combined forces (64 to 68 ships and 7,000 to 13,000 men) landed in Cangrejos, approximately three miles west of San Juan. San Juan's military forces, which included, among others, the Regimiento Fijo de Puerto Rico (Resident Regiment of Puerto Rico) and the Militias Disciplinadas (Trained Militias) were outnumbered by the invaders by a ratio of almost three to one. Admiral Harvey blockaded the San Juan Harbor while Abercromby established his operations headquarters in San Mateo parish overseeing all of San Juan and the Martín Peña Bridge. Abercromby's strategy was to take the Martín Peña bridge in order to block Spanish reinforcements from the south and bombard San Gerónimo and San Antonio from Miramar to gain access to and cross the San Antonio Bridge into the San Juan islet. British forces included the Royal Marines, made famous by their later defeat of Napoleon's troops in Egypt. Then-Governor of Puerto Rico Field Marshal Don Ramón de Castro y Gutiérrez, a brilliant strategist, prevented the British from advancing and frustrated their conquest of San Juan. The San Gerónimo and San Antonio sustained heavy damage from the constant bombardment during the two-week siege on the city. Chronicles describe the defenders shooting their muskets and cannons from behind sandbags because of the devastation their forts sustained. Both San Gerónimo and San Antonio were eventually rebuilt and expanded. San Gerónimo is