Medium includes graphite. The annotation on this drawing suggests that it depicts German U-boat U.153. However, this may be a misidentification as the vessel shown is flying a French flag. U.153 surrendered to the Allies at Harwich on 24 November 1918. Although originally supposed to be allocated to France, it was in fact retained by the British. Laid up at Portsmouth, it was towed into the English Channel on 30 June 1921 and scuttled. It is possible that U.153 may have temporarily flown the French flag, but another possibility is that this drawing depicts a different vessel, U.157, which was transferred to France on 8 February 1919 and was broken up at Brest from July 1921.