The two photographs on Page 21 were taken by an RE8 of 6 Squadron, part of the squadron's aerial reconnaissance operations over the Western Front during WW1.

 

The photographs were were taken over an area just to the south of the St Eloi crossroads, as defined by mapping coordinates 28. O. 2. C and 28. O. 2. D. The first photograph was taken on the 1st May 1917 and the second on the 4th June 1917, 3 days before 19 mines were detonated beneath the German lines along the Messines ridge at the start of the Battle of Messines