During World War I, Germany laid more than 43,000 mines that claimed some 500 merchant vessels. The British Navy lost 44 warships and 225 auxiliaries to mines. The purpose was to interrupt the flow of supplies to Britain and to hamper the British fleet. Mines were most often set near harbors and inlets, as these were areas of high traffic. Great Britain reacted to the threat by setting up an intelligence network to identify, map, and distribute information about the location of mines.
One such map produced by British Naval Intelligence is shown here from the William Rea Furlong map collection, which is held by the Geography and Map Division. The once secret document depicts the general situation of minefields surrounding Great Britain on August 19, 1918. It was not meant for navigating through a specific minefield, as those were mapped separately at greater scale that showed more detail. The map also illustrates areas where the British had placed mines to restrict the movement of German military and commercial vessels.
As the legend indicates, areas hatched in red are dangerous due to moored British mines. Numbers in red within the black rectangles indicate the number of moored enemy mines swept up and destroyed in that area in the two-week period between August 5th and August 19th, 1918. The red asterisk-like symbols indicate harbors that have a swept channel through which ships can enter and leave safely. Closer looks at the map show the extent of naval minesweeping operations, from the English Channel to the north coast of Scotland:
Secret maps, such as this one, were essential to the British Navy to confidentially report on the status of German minefields to commanders and policymakers. This map in particular boasts of the British Navy’s successful minesweeping operations that minimized the threat posed by German mines.
Good afternoon, I was wondering if you would be able to advise where I could find some images of A Mark Sea Mines for either private or public use please. I have scoured the internet and have unsuccessful in locating these types of mine specifically? Your assistance would be very much appreciated. Kind regards
While cleaning out my fathers house, I came across some original British Intelligence maps…. some in good shape, some very fragile…. would like more information on them if possible and wondering if you would be able to help
Greetings. This the author of the Library of Congress blog on which you posted your message.
In what way may I be of assistance with the maps in your possession?
Ryan Moore, MA, MLS
Library of Congress
Email: [email protected]
Am of the opinion that it was the British who first dropped mines into the water hoping to blockade the N Sea and restrict German movement. Would you please comment on this. German retaliation consisted of their mining the British Isles. Any information would be greatly appreciated.