Spanish Fortification

Due to its strategic location at the entrance of San Juan Bay, Isla de Cabras provided a strategic point for an effective crossfire with Fort San Felipe del Morro to prevent incoming ships from entering. It also provided defenses for the entrance of the Bayamón River on the other side of the islet.

Leper Colony

At the end of the 19th century, a leper colony was established on the island. On December 17, 1876, the governor of Puerto Rico, Segundo de la Portilla, set the first stone of the official building to house lepers, which was completed in 1883. However, it is believed that the colony was established prior to construction of the building.^{[citation needed]}

Upon the occupation of Puerto Rico by American troops in 1898, management of the building was handed over to the government of the island. According to the 1910 US Census, there were 35 people living on the island at that time.^{[citation needed]}

In 1926, a leper asylum was built on the main island (Trujillo Alto) next to a church, and the residents of the colony were moved there. However, the original building still stands on Isla de Cabras.

American Fortification

In the 1940s, the United States built Fort Amezquita (named for Juan de Amézqueta), a few hundred feet from El Cañuelo. The fort was initially called the "Cabras Island Military Reservation". During World War II this fort served as a "concrete gun battery" for the US Army Coast Artillery Corps. In November 1940 the US Army transferred the barrels of three 12-inch coastal guns from Fort Delaware, Delaware; two of these guns were mounted in the fort as Battery Reed with the third as a spare. They were on long-range M1917 barbette carriages and protected by concrete casemates.^{[citation needed]}

Shooting Range & Recreational Park

In recent years, the grounds that belonged to Fort Amezquita were converted into a shooting range and training area by the P.R.P.D. Ownership of the remaining acres of land were under legal dispute, until they were finally transferred to the Department of Sports and Recreation and opened to the public as the Isla de Cabras Recreational Park,^[2] which is equipped with several gazebos and includes a beach for swimming and fishing.