Fascinating World War I-era map showing an oft-forgotten aspect of the Great War, namely the sinking of Allied vessels off the U.S. East Coast by German submarines.
The map shows the sinking of a total of 20 vessels, most of them off the coasts of Delaware and New Jersey, but some as far south as the entrance to the Chesapeake Bay.
An explanatory note below the map reads as follows:
The sinking of two Norwegian steamships by a German submarine on June 10 about 100 miles east of Cape Charles raised the number of vessels attacked since May 25 to over a score. Most of the ships lost belonged to the United States, the second heaviest sufferer being Norway, with four vessels. The above map shows the range within which the German U-boat, or U-boats, (the number of the raiders is still in doubt,) operated during the six-teen days since the attack on shipping in American home waters began. It will be seen that the submarine campaign has been carried almost to the threshold of America's greatest shipping centre, and that the ships have been sunk on the busiest traffic routes along the coast as far south as Cape Charles. The American naval authorities were first aware of the German submarine's presence on June 2, and although naval and aerial patrols have been busy ever since, the U-boat has been able to elude detection and continue its campaign of destruction.
Based on the language of the caption, we can conclude that the map was probably produced in Great Britain.