Germany continues with lying sea mines in British waters according to the U.S. Joint Intelligence Committee. Daily summary dated 15 January 1942

An item reported that Germany renewed on a considerable scale lying sea mines in the vicinity of the United Kingdom especially the Thames causing daily losses.

Source

Map Room Papers (Roosevelt Administration), 1942 - 1945. U.S. Joint Intelligence Committee. Daily summary dated 15 January 1942 No. 36.