Nazi submarines in the Caribbean

Most people imagine the Second World War happening far away from Puerto Rico. In reality, German U-boats spent much of 1942 hunting Allied shipping right in the Caribbean, and San Juan was already sitting inside a U.S. Navy patrol network built to watch exactly that threat.

The U.S. Navy's patrol squadron VP-51, flying Consolidated PBY Catalina seaplanes, began neutrality patrols along the Lesser Antilles out of San Juan starting on September 13, 1939, more than two years before the United States formally entered the war, a sign that Washington already saw the Caribbean as a strategic concern.

Once the U.S. declared war in December 1941, the German Kriegsmarine launched what it called Operation Neuland, extending unrestricted submarine warfare to the Caribbean Sea. The target was Allied oil and bauxite traffic, since the Caribbean supplied both the Venezuelan oil refined at Curaçao and Aruba and the bauxite used to make aluminum for warplanes, two materials without which the Allied war effort could not operate.

Eleven German and allied Italian submarines were sent to the Caribbean in January and February 1942 specifically to stretch Allied anti-submarine resources across a wide area. In its first weeks, the campaign sank a significant tonnage of Allied tankers near Aruba, Trinidad, and other points in the region.

Puerto Rico sat fully inside this contested traffic corridor, and its strategic position drove a major U.S. military buildup on the island across the war years, including the construction of Borinquen Field near Aguadilla, a military airfield later renamed Ramey Air Force Base and known today as Rafael Hernández Airport.

None of this meant a land battle ever reached Puerto Rico. But the U-boat threat meant the island's coastal waters, shipping, and economy were touched head-on by the war, a chapter of its wartime experience that rarely appears outside specialized histories, overshadowed by the more famous battles fought thousands of miles away.

Sources: Operación Neuland; Borinquen Field. Freeze 2026-08-22.