In the summer of 1918, five large German submarines (U-boats) crossed the Atlantic and operated against the lightly protected shipping off the North American coast. Several of the U-boats would get as far south as the North Carolina coast, where they sank three ships just a few miles from the Outer Banks.
The sinking of Diamond Shoals Light Vessel and the Merak
The largest of these German submarines was the U 140, an “U-cruiser” designed to overwhelm merchant ships, even if fitted with defensive armament, with its superior guns. U 140 sailed from Kiel on July 2,1918, under the command of Korvettenkapitän Waldemar Kophamel, an experienced submarine officer who had been awarded the Pour le Mérite (“Blue Max”), Prussia’s highest military honor.
By August 4, U 140 was off the Virginia coast, where she sank the large armed tanker O.B. Jennings after a 22-minute artillery exchange. The next day, 110 miles east of Cape Hatteras, the U-cruiser stopped and scuttled the schooner Stanley M. Seaman.
U 140 then turned toward the Outer Banks, where she sighted two vessels on the early afternoon of August 6. She fired a single shell towards each to compel them to stop. When the American steamer Merak, en route from Norfolk to Chile with a cargo of coal, did not stop, the U-boat fired on her. The Merak eventually went aground, and the crew abandoned ship.
The second ship was the Diamond Shoal Light Vessel (LV-71). It began sending radio warnings, so U 140 opened fire on it to stop the transmissions. The barrage prompted the crew to abandon ship, as well. (Hatteras residents, not too far away, could hear the naval gunfire.) The U-boat then proceeded to finish off Merak with scuttling charges before sinking the light vessel by gunnery. There were no casualties.
U 140 remained off the Outer Banks for another day, before patrolling further north. She arrived back in Germany on September 20, 1918, having accounted for over 30,00 tons of shipping.
The sinking of Mirlo and the rescue of its crew
Nine days after U 140 had left Kiel, U 117 embarked from the same port on its mission to lay a supply of 34 mines along the U.S. coast. The first of these mines were deployed off Barnegat, New Jersey on August 13, and as the U-boat continued southward, it laid additional mines off the Delaware and Virginia coasts.
U 117’s commander planned to lay the last nine of her mines north of Cape Hatteras near the Wimble Shoal Buoy. While doing so on the afternoon of August 16, the British tanker Mirlo, en route from New Orleans for the Thames via Norfolk, came into view. U 117 suspended minelaying and proceeded to attack the merchant vessel, firing a single torpedo at an estimated range of 400 meters. It struck home, igniting the Mirlo’s cargo of gasoline. The tanker exploded 10 minutes later.
By then though, the tanker’s crew had abandoned ship. Nine crewmembers were killed when a lifeboat capsized along the tanker. A boat from the Coast Guard’s Chicamacomico Lifesaving Station brought in the remaining 42 crewmembers in one of the most heralded rescues in U.S. maritime history. Launching despite heavy seas, the station’s Surfboat No. 1046 navigated its way around walls of flame so intense that they blistered the boat’s paint to reach the Mirlo’s remaining lifeboats, tow them out of danger, and then bring the survivors ashore. The surfboat’s six-member crew was alter awarded gold medals by the British Government and the Grand Cross of the American Cross of Honor for their efforts.
U 117 laid the last of her mines and then began the voyage back to Germany, arriving home on September 22, 1918 after having destroyed 27,000 tons of shipping. In addition, the battleship USS Minnesota struck one of the mines that U 117 had laid on August 29 off the Delaware coast; the warship was out of action for five months. The Cape Hatteras minefield proved to be ineffective.
At the end of World War I, surviving U-boats were surrendered to the Allies. U 117 and U 140 were among the six German submarines allocated to the United States. In June and July 1921, respectively, both were sunk as targets during military exercises off the Virginia coast.
Dictionary of American Naval Fighting Ships entries on both U 117 and U 140:
Spindler, Arno, Der Krieg zur See: Handelskrieg mit U-booten, Vol.5
“German Submarine Activities on the Atlantic Coast of the United States and Canada”, Navy Department Office of Naval records and Library Historical Section, Publication Number 1:, Washington, D.C. Government Printing Office, 1920 (Available via Google Books).