This was a German effort to infiltrate intelligence and sabotage agents into the eastern USA (30 November/30 December 1944).
The agents involved were Erich Gimpel and William Colepaugh, the former a German and the latter a German-American defector. The two men were tasked with gathering information about the ‘Manhattan’ Project and attempting sabotage if possible. The men left Kiel in U-1230 and landed at Hancock Point, Maine, on 30 November before making their way to New York.
Thereafter the operation was a complete failure. Colepaugh surrendered himself to the FBI on 26 December, revealing the details of the entire plan, and Gimpel was arrested four days later. Both men were sentenced to death, but their sentences were later commuted. Gimpel spent 10 years in prison and was deported to Brazil, while Colepaugh was released in 1960.