Neutrality patrol

On September 3, 1939, the British and French declarations of war on Germany initiated the Battle of the Atlantic. The United States Navy Chief of Naval Operations (CNO) established a combined air and ship patrol of the United States Atlantic coast, including the Caribbean Sea, on September 4. President Franklin D. Roosevelt declared the United States' neutrality on September 5, and declared the naval patrol a Neutrality Patrol.

On September 4, 1939, the CNO ordered the Atlantic Squadron to establish a combined air and ship patrol to observe and report the movements of warships of warring nations within a line extending east from Boston to 65 degrees west and thence south to the 19th parallel and seaward around the Leeward and Windward Islands. The concept of a naval Neutrality Patrol within that zone was presented to a Conference of Foreign Ministers of the American Republics convened in Panama on September 25. After considerable debate, the conference agreed on October 2, 1939, to extend the neutrality zone southwesterly parallel to the northeastern coast of South America approximately 300 miles (480 km) offshore.

Despite the name, the Neutrality Patrol greatly favored the British as the Royal Navy had far greater access to the Atlantic. While German naval shipping and military aircraft could operate only from the coast of Europe to intercept British ships, German ships could be intercepted by British military forces operating from the United Kingdom, Canada, Newfoundland, Labrador, Gibraltar, Sierra Leone, Gambia, Nigeria, South Africa, British Togoland, the British Cameroons, the Falkland Islands, South Georgia, Saint Helena, Ascension Island, Bermuda, Jamaica, Trinidad, Barbados, The Bahamas, the British Leeward Islands, the British Windward Islands, the British Virgin Islands, British Honduras, and British Guiana.

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