Inscribed by Wyllie 'UB77' in red, this is a reasonable starboard quarter depiction of a German UB III-type submarine, of which this boat was one. She was built by Blohm & Voss at Hamburg, launched on 5 May 1917 and commissioned on 2 October 1917. She surrendered on 16 January 1919 after the end of the war and was broken up at Swansea in 1922. Two unrelated bow-on studies of Thames barges under full sail, in pencil, have been added over the watercolour wash at lower left.