Silent Enemy, Sudden War: America’s First U-Boat Encounter

World War 2 US Navy Helmet & Mk 2 Knife

In the months preceding the United States’ official entry into World War II, the Atlantic Ocean had already become an undeclared battlefield. While the U.S. maintained a policy of neutrality, escalating tensions with Nazi Germany—particularly in the Atlantic—set the stage for eventual conflict. One of the most consequential moments in this prelude to war occurred on September 4, 1941, when the USS Greer (DD-145), a U.S. Navy destroyer, engaged in a hostile encounter with German U-boat U-652. This event marked the first exchange of fire between American and German forces during WWII, significantly altering U.S. naval policy and public sentiment.

Throughout 1941, President Franklin D. Roosevelt increasingly supported Allied efforts through programs such as Lend-Lease and intensified maritime patrols in the North Atlantic. Though officially neutral, the U.S. Navy was tasked with escorting Allied convoys and monitoring German U-boat activity. These missions, while framed as defensive, brought U.S. forces into closer and more frequent contact with German submarines.

The USS Greer, a Wickes-class destroyer, was assigned to patrol duties in the North Atlantic, often tracking and reporting submarine contacts to the Royal Navy. On the morning of September 4, 1941, the Greer was en route to Iceland when it became involved in a significant confrontation.

While operating southeast of Iceland, the USS Greer received information from a British aircraft that a German submarine had been sighted ahead. The destroyer made sonar contact with U-652 and began shadowing the submarine for several hours, relaying its position but not engaging.

At approximately 12:40 p.m., the situation escalated when the German U-boat fired a torpedo at the Greer. The destroyer responded by taking evasive maneuvers and dropping depth charges. A second torpedo was fired shortly thereafter, also missing its target. Over the next two hours, the Greer conducted a series of depth charge attacks, though no confirmed damage to U-652 was recorded. The engagement ended without casualties on either side.

The Greer Incident, as it came to be known, had immediate political ramifications. On September 11, 1941, President Roosevelt addressed the nation via radio in his famous “Fireside Chat”, accusing Nazi Germany of initiating unprovoked attacks against American ships. He declared a new policy: the U.S. Navy would shoot on sight any Axis vessel found in waters deemed vital to American defense.

This marked a clear departure from strict neutrality and signaled an aggressive posture in the Atlantic. Roosevelt’s “shoot-on-sight” order effectively meant that the United States was now engaged in naval warfare with Germany, albeit unofficially. The incident also contributed to a hardening of American public opinion against the Axis powers, helping to prepare the nation psychologically for full-scale involvement in the war following the Japanese attack on Pearl Harbor three months later.

Germany, in response to U.S. accusations, claimed that the Greer had acted provocatively by tracking the U-boat and cooperating with British forces. German officials argued that the U-boat fired in self-defense. Despite these assertions, the event was widely interpreted by the international community as German aggression against a neutral power.

The encounter between the USS Greer and U-652 marked the beginning of a quasi-war between the United States and Nazi Germany in the Atlantic. Subsequent incidents, including attacks on the USS Kearny and the USS Reuben James (the latter resulting in American deaths), further eroded the distinction between neutrality and belligerency.

Today, the Greer Incident is remembered not only as the first direct military engagement between U.S. and German forces in WWII, but also as a critical turning point in the United States' path to full involvement in the global conflict.