English: Aerial photograph, St Eloi, near Ypres, Belgium, 19 March 1916. This aerial photograph shows the area around St Eloi, near the Ypres salient. It is interesting that Field Marshal (Earl) Haig (1861-1928) kept copies of aerial photographs of this area taken directly before and after the huge detonation of British mines on 27 March 1916, which preceded an Allied advance.

Haig described the preparation of these mines in his dispatch of 19 May 1916, 'Below ground there is continual mining and counter-mining, which, by the ever-present threat of sudden explosion and the uncertainty as to when and where it will take place, causes perhaps a more constant strain than any other form of warfare.'
[Original reads: 'Photograph No KX.465 / Date taken 19/3/16 / Sheet 28 / Area O / No. 6 Squadron / Chief features shown:- 4,300 ft. ST ELOI'. On the back of the photograph is written 'SCALE 20000' and 'TAKEN BY NO 6 SQUAD.']

http://digital.nls.uk/74549740