Last updated: October 16, 2026
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Charlotte Amalie, US Virgin Islands
City of Charlotte Amalie
The US Virgin Islands played a strategic role in World War II, strengthening the US presence in the Caribbean. The US originally purchased the island territory from Denmark on March 31, 1917, and granted full American citizenship to its citizens in 1927.
The city of Charlotte Amalie had strategic military importance to the United States due to its position on the island of Saint Thomas. It served as a hub for Allied military operations in the Caribbean Sea, helping to protect the Panama Canal and other US and Allied interests in the region.
Before 1941, the US military built a Marine headquarters and barracks in Charlotte Amalie. They built a quartermaster store along the harbor and a communications center at Fort Christian. They also built a naval hospital and a seaplane base.
As the war years progressed, the installations grew to include an air station and a submarine base in bays west of downtown as well as coastal defenses on islands in the main harbor. Hassel Island was home to an updated naval station and fortifications on Water Island and hillsides strengthened harbor defenses. These facilities contributed to the US military’s success in countering German and Italian submarine activity in the Caribbean Sea. Submarines and patrol aircraft from Charlotte Amalie protected convoys from South America transporting fuel oils and supplies vital to the war effort.
Charlotte Amalie honors its World War II contributions with ceremonies on Veteran’s Day and Transfer Day (a territorial holiday occurring on March 31). The Virgin Islands Port Authority and the University of the Virgin Islands spotlight World War II era structures. The St. Thomas Historical Trust provides online content and tours of harbor sites, including those of Hassel Island. Fort Segarra, Battery 314, on Water Island preserves concrete defensive structures from World War II, including pill boxes and gun mounts.