In the final year of World War I, Germany made its first attempt to wage submarine warfare off faraway shores. Large, long-range U-boats (short for unterseeboot or "undersea boat") attacked Allied shipping off the coasts of the U.S., Canada and West Africa in a desperate campaign to sidestep and scatter the lethal U-boat defenses in European waters.

Commissioned in 1917, U-156 raided commerce, transported captured cargo and terrorized coastal populations from Madeira to Cape Cod. In July 1918, the USS San Diego was sunk as it headed into New York Harbor—the opening salvo in a month-long series of audacious attacks by U-156 along the North American coast. The author chronicles the campaign from the perspective of Imperial Germany for the first time in English.