U-151, seen from a Spanish passenger liner.
June 2 1918, Atlantic City–The cruises of the “submarine merchant ship” Deutschland and her sister boats in 1916 had demonstrated that Germany had U-boats that could cross the Atlantic. They were converted to military purposes after America entered the war, but had not crossed the Atlantic since. In part, this was because the Germans did not want to overly antagonize the Americans, but also because such a voyage would be much more difficult as they could no longer refuel in American ports. U-151 was the first to make the journey, arriving off the eastern seaboard in late May, laying mines at the entrance to the Chesapeake Bay and the Delaware River, and attacking any American merchant ships she encountered. The United States did not have a significant anti-submarine effort off her own coast, as most of their effort had gone to the other side of the Atlantic. As a result, U-151 could safely follow prize rules: stopping ships on the surface, letting those on board evacuate, and then sinking the ships with charges.
On June 2, U-151 sank five ships this way off the coast of New Jersey. A sixth, the passenger liner Carolina, en route from San Juan to New York, attempted to flee and the Germans fired shells in her direction. Her captain, fearing loss of life if the shells struck, stopped and evacuated the vessel, after which the Germans finished off the ship with more shells. During a storm that night, one of the Carolina’s lifeboats overturned and thirteen on board drowned. The U-151 remained off of the American and Canadian coasts for the rest of June. On June 18, U-151 had its only encounter with a Navy vessel, the USS Von Steuben, formerly the German commerce raider Kronprinz Wilhelm; a torpedo from the former and a depth charge from the latter both narrowly missed.
Today in 1917: Grand Duke Nicholas Arrested