In the closing weeks of World War II in Europe, American intelligence determined that a detachment of German submarines had been dispatched to launch a cruise missile attack on the East Coast of the United States. The U.S. Navy deployed forty-six ships and dozens of aircraft to annihilate the incoming submarine wolf pack. The battle that followed saw hundreds of lives lost at sea, and showed American intelligence services at their very best— and worst.
Nazi Germany was the first nation to deploy cruise and ballistic missiles in combat. The V1 “Buzz Bomb” could fly more than 180 miles powered by a pulse jet before slamming into its target. The slightly longer-range V-2 could shoot up to fifty-five miles high in its ballistic trajectory before plunging unstoppably towards the ground. Both weapons killed thousands of civilians in London and Western European cities. However, the United States remained far out of reach.
Nonetheless, the possibility that the so-called “vengeance weapons” might be mounted on submarines and used to sow chaos along the eastern seaboard of the United States did not escape Allied commanders. After the FBI interrogated a German spy rescued from a destroyed U-Boat, J. Edgar Hoover warned Washington on October 25, 1944, that Germany was planning a submarine-launched buzz bomb attack on the United States. Supposedly, reconnaissance photos depicted what appeared to be launch rails on U-Boats penned in Norway. Two more spies, arrested in December 1944, gave similar accounts of a submarine-launched missile program. In Berlin, minister of war production Albert Speer promised that missiles would fall on New York by February.
Recommended: This Is How China Would Invade Taiwan (And How to Stop It) .
Recommended: The Story of the F-52 Fighter .
Recommended: The 5 Biggest Nuclear Bomb Tests (From All 6 Nuclear Powers) .
Most Allied commanders were skeptical that there was a genuine threat to the continental United States—save for certain leaders of the U.S. Navy. In January 1945, the U.S. Atlantic Fleet organized two coastal defense task forces that would operate from a forward base in Argentia, Newfoundland. The fleet’s commander, Adm. Jonas Ingram, warned the press of probable “robot bomb” attacks launched by a “half-dozen submarines” in the coming months.
At the heart of each of the detachments were two escort carriers which could carry two dozen patrol planes each. Antisubmarine aircraft had proven highly effective at detecting surfaced U-Boats, and had sunk more than their fair share.
Accompanying the “jeep” carriers were more than twenty destroyer-escorts (DEs), small antisubmarine vessels equivalent to a modern frigate. Benefitting from sonar, radar and air patrols, the DEs were also armed with Hedgehogs—arrays of twenty-four spigot mortar charges that could be launched up to two hundred meters away. Unlike depth charges, Hedgehogs detonated on contact with a submarine’s hull, often sank the target in one or two hits, and could not be easily evaded after launch.
The U.S. Navy had a key advantage—the British had broken the German’s top-level code way back in 1941 and had been closely following the movements of German submarines since then, with the exception of a ten-month period in 1942 when the Kriegsmarine upgraded its encrypting machines.
In March, the Allies intercepted a message from German Admiral Godt dispatching seven Type IX long-range submarines to “attack targets in American coastal zone” as part of an attack group awesomely codenamed Seewolf. Another intercept message diverted to the U.S. coast the U-Boat of Captain Friedrich Steinhoff, who had earlier commanded U-511 in tests of rocket artillery that could be fired underwater.
The Navy was convinced that these signs all heralded an attack by missile-launching U-Boats, and sprang into action, initiating Operation Teardrop and diverting merchant traffic away from the battle zone. By April 12, the First Barrier force had established a “barrier line” 105 miles from north to south to screen for approaching submarines. A dozen DEs stood sentinel on the line, while the escort carriers and their escorts remained further back.
Meanwhile, the Kriegsmarine continuously micromanaged the approach vectors of its submarines via radio transmissions. These were intercepted by Allied intelligence, giving the U.S. Navy a fairly good idea of where the U-Boats were approach from. However, bad weather prevented the aircraft aboard the escort carriers from patrolling as actively as desired
The diesel-powered Type IX submarines could travel underwater a maximum of only sixteen hours at roughly 4.5 miles per hour before their batteries ran dry. Therefore, the German submarines typically surfaced at night to move at much higher speeds and recharge their batteries—but still did so at a risk.
On April 15, the submarine U-1235 was detected on radar shortly after midnight, about midway between the coasts of France and Newfoundland. Though it quickly submerged, the U-Boat was sunk under a sustained Hedgehog attack by the USS Stanton and USS Frost .