This very dramatic and broadly handled watercolour appears to be a study of 'Iron Duke'-class battleships firing their main armament at sea in the 1915-17 period, before their bridges were enlarged. The leading ship is flying a flag signal but no battle ensign, which is one reason for believing the image shows a gunnery exercise, not a sea action. Another is the very strong probability that this is in fact a preliminary version of the watercolour reproduced (in colour) in Wyllie's co-authored book 'More Sea Fights of the Great War (1919) f. p. 72, with the title quoted above. The basic composition and viewpoint is the same, and disposition of the guns on the leading ship in particular suggest that is the case, though the finished version is more developed.