First Line of Defense

The first line of defense was the outermost landward defensive line of the walled city of San Juan, running along the eastern edge of the San Juan Islet and consisting of fortifications built at different times, including San Jerónimo Fort, the San Antonio Fortified Bridge, the San Jerónimo Magazine, and its guardhouse, all shown on a 1772 plan by Thomas O'Daly. From then on, Thomas O'Daly and Juan Francisco Mestre reinforced the line into a sophisticated network linked by parapets that protected troop movement from enemy artillery and followed the Islet's eastern shore from Escambrón Point to the mangroves of the San Antonio Channel. An early version of San Jerónimo Fort had been built in 1532 to protect the eastern coast overlooking El Boquerón, and during the 17th and 18th centuries it was improved into the fort that, together with the fortified San Antonio Bridge, formed the key components of this line. In April 1797, 3,910 English soldiers under Sir Ralph Abercromby landed from 60 vessels at Cangrejos Cove to the east, but the fort, commanded by Coronel Teodomiro del Toro, resisted the bombardment and forced their retreat; according to tradition, del Toro rebuilt by night what the English destroyed by day. The fort was rebuilt by 1799 after severe damage and remained a military post until the early 20th century. Some elements of the first line stayed in military use until the beginning of the 20th century, but afterward the system was gradually mutilated, first by construction of a horse racetrack in the El Escambrón area, and only scattered sections and pieces survive today.

San Juan, Puerto Rico · United States