Puerto Rico took on a new strategic importance under American administration. The opening of the Panama Canal, a vital waterway linking the Pacific and the Atlantic, drew large amounts of shipping through the region and the old fortifications of San Juan were once again called into service as guardians of the Caribbean.
From World War I to the Cold War, Puerto Rico featured prominently in United States strategy in the Caribbean. The United States Antilles Command, headquartered in part at San Cristóbal (which was renamed Fort Brooke), coordinated allied efforts to protect the vital sea lanes in the eastern Caribbean and central Atlantic. San Juan became headquarters for American forces protecting shipping lanes and monitoring hostile military activity in the region. The military patch for the Antilles Command featured a stylised garita, drawing inspiration from the sentry boxes of San Cristobal and El Morro.
As World War II approached in the late 1930s, the United States began to expand its military presence in Puerto Rico. By 1943 there were over 55,000 service personnel deployed around the island. As part of Fort Brooke, San Cristobal was the duty station for a variety of communications, air defence, and support service units.
The coming of World War II started a building boom in and around San Juan. To face the challenges of modern warfare, the United States expanded San Juan’s defences. Soldiers were deployed in new coastal fortifications and anti-aircraft batteries around the city. Fort Amezquita, located on the Isla de Cabras, was equipped with 12-inch guns, controlled by commanders at Fort Brooke, protected by concrete bunkers. New roads, power line and telephone lines sprung up around San Juan almost overnight. Among the largest projects was the construction of the new port facilities, including a dry dock for the the U.S. Navy.
Puerto Rico’s strategic importance was made clear once again in World War II. Aircraft destined for North Africa or Italy would refuel at air bases in Puerto Rico before continuing to South America, and then to West Africa and finally on to bases in the Mediterranean region.
During the 1950s and 1960s the United States used its bases in Puerto Rico to extend its influence throughout the Caribbean and to keep watch on its Cold War rivals – Cuba and the Soviet Union.
- Information signs at Castillo San Cristóbal
- Information signs at Castillo San Felipe del Morro