The American Fleet complicated Germany’s only threat in the Atlantic: the U-boats. Despite Hitler’s restrictions, the Germans began to zero in on American warships. On June 20, 1941, U-203 tracked and tried to get into a firing position against the battleship USS Texas in the area of sea where the neutrality zone and Hitler’s war zone overlapped. Although U-203 failed, another U-boat sank the merchantman SS Robin Moore on June 27. But the coordination between American and British naval staffs enabled them to reroute most of the convoys from the paths of the German submarines. The rerouting worked so well that many of the U-boat sightings were only of American warships, which they were not allowed to attack. In July, the United States occupied Iceland, a European territory. This was tantamount to a declaration of war against Germany.
On July 7, the U.S. Navy landed the Marines professionally and with dispatch. Roosevelt ordered a war zone around Iceland and notified Stark and Army Chief of Staff General George C. Marshall that “the approach of any Axis force within 50 miles of Iceland was to be deemed conclusive evidence of hostile intention and therefore would justify an attack by the armed forces of the United States.”
Admiral King immediately followed the presidential order with “Special Instructions Concerning U.S. Navy Western Hemisphere Defense Plan No. 4—(WPL-51)” on July 25, which ordered the American Fleet to escort American merchant ships traveling to Iceland. This was later amended to include “shipping of any nationality.” The next important contingent to arrive on Iceland, on August 6, was U.S. Navy Patrol Wing 7, a contingent of seaplanes.
For the Americans, their presence in Iceland put U.S. troops and ships squarely into the Battle of the Atlantic. In short order the Americans turned Iceland into a virtually impregnable military fortress, and it became the most vital Allied outpost in the Atlantic Ocean. In his orders to King to commence the occupation, Stark wrote, “I realize that this is practically an act of war.”
U.S. Navy on Convoy Duty
As America geared up for direct convoy escort, the people at home sensed this undeclared war. In July, the president decided to put Navy plans for escorting transatlantic convoys into effect. He told Churchill this at a subsequent meeting in Newfoundland.
At that secret meeting in August, Roosevelt made several promises to Churchill, including to further project American naval strength into the North Atlantic. He forged a “concrete agreement” that committed the U.S. Navy to convoy duty. He also promised that the U.S. Navy would attack U-boats. America was at war, only Congress and the public did not know it. Back on July 29, at Senate hearings to investigate the charges that American naval vessels were convoying ships or attacking German naval vessels, the chairman of the Committee on Naval Affairs asked Knox and Stark point-blank if the Navy was escorting or planning to escort. Both flat-out lied when they emphatically said, “No.”
But American warships violated all technical definitions of neutrality by escorting convoys beginning in August. Churchill reported to the War Cabinet that Roosevelt said to him at their face-to-face meeting in August, “I would wage war, but not declare it.” Upon his return to Washington, Roosevelt went right to work to fulfill his commitments.
At the beginning of third year of the war, the British Admiralty was overwhelmed by urgent operational tasks around the world. The most demanding and difficult was the protection of Atlantic convoys, Britain’s lifeline. Amid great secrecy, important modifications in the Royal Navy’s mission took place in September. The most significant was America’s assumption of responsibility for escorting convoys on the Canada-Iceland leg of the North Atlantic run. The entry of the “neutral” American Navy into this “undeclared war” also greatly affected the deployment and operations of Canadian forces. King’s control and resources now included the entire Atlantic-based Canadian Navy. Admiral King, in consultation with the Admiralty, made substantial changes in convoy procedures in the Western Atlantic.
Roosevelt’s “Shoot on Sight” Order
On September 1, the Denmark Strait Patrol began operation. Its assignment was to close to Axis ships the entrance into the Atlantic between Iceland and Greenland while the British Home Fleet took responsibility for the other entrance between Iceland and the Faroes. Admiral King even went so far as to agree to put American ships of the Atlantic Fleet under temporary British command for the purpose of hunting down German surface ships that broke through the Denmark Strait.
On the same day, Admiral King ordered the reorganized Atlantic Fleet to begin escort duty between Newfoundland and Iceland. Naval vessels in the North Atlantic were further required specifically to operate under wartime conditions. The first American-escorted convoy was planned for September 16, but a clash between an American destroyer and a German U-boat led Roosevelt to permit American ships to fire at enemy submarines first in this undeclared war.
On September 4, German U-652 attacked the American destroyer USS Greer on a supply run to Iceland. The commander of U-652 believed he had been attacked by Greer, when actually it had been a British seaplane. Greer returned fire with depth charges. Neither ship was damaged, but the situation in the Atlantic had been shattered. A de facto war now existed between the United States and Germany.
Roosevelt used the incident to issue his “shoot on sight” order on September 11. At a conference with Hitler, Admiral Raeder analyzed the strategic implications of Roosevelt’s orders and stated, “German forces must expect offensive war measures by these American forces. There is no longer any difference between British and American ships.” The German naval staff characterized the orders as a “locally restricted declaration of war.”
Stark informed Admiral Thomas C. Hart, commander of the U.S. Asiatic Fleet, in Manila, “So far as the Atlantic is concerned we are all but, if not actually, in it.”
The skirmish brought the American public into the undeclared war. After Roosevelt addressed the American people, 62 percent supported the president’s decision and America’s defense of freedom of the seas. Immediately, the Atlantic Fleet began to receive daily reports of U-boat positions in the Atlantic derived from the British Admiralty Submarine Tracking Room.
War Finally Declared
Convoy HX150, the first U.S. protected convoy, sailed on September 16. The next battle was on September 20 between the destroyer USS Truxton and a German submarine. Again neither warship was damaged. America expanded its responsibility further into the South Atlantic when, on September 29, Brazil opened two of its ports, Recife and Bahia, to American ships. By the beginning of October, the U.S. Navy was fully integrated in the two-thirds of the Atlantic Ocean that was now “American.” The U.S. Navy worked alongside the Canadian Navy escorting slow convoys along the Canadian coast. By October 1941, the Atlantic Fleet consisted of seven battleships, five cruisers, eight light cruisers, 87 destroyers, and four aircraft carriers, more carriers than in the entire Pacific.
On October 17, the destroyer USS Kearny was damaged by a torpedo off the coast of Greenland, leaving 11 dead and 24 wounded. The crew confined the flooding to the forward fire room, enabling the ship to get out of the danger zone. After power was regained in the forward fire room, Kearny steamed to Iceland. On October 31, the destroyer USS Reuben James, while escorting a convoy from Halifax, Nova Scotia, was torpedoed and sunk by U-552 near Iceland with a loss of 115 lives. She was the first U.S. warship sunk by the Germans in the Atlantic.
On November 2, to help beef up the Atlantic Fleet, Roosevelt transferred the Coast Guard to U.S. Navy command. Such action is usually initiated after a declaration of war. By November 7, Senator Robert Taft commented, “The battle of the Atlantic is now an American undertaking.” Four days later, the U.S. Navy achieved its first victory against the German Navy with the capture of the German blockade runner Odenwald off the coast of Brazil by the cruiser USS Omaha and the destroyer USS Somers. Also in November, the president ordered American troops to occupy Dutch Guiana by agreement with the Netherlands government in exile.
Within weeks, Japan’s surprise attack on Pearl Harbor and Hitler’s equally surprising declaration of war carried the United States into a declared war.
America’s participation in an undeclared naval war in the Atlantic reaped enormous benefits toward its total war effort and helped carry Britain through its toughest two years. Due to secrecy, the importance of the undeclared war was not realized by the American people at the time, but its contribution to Allied victory was as important as any of the “real” war.