14.6.18 LONDON GAZETTE: 2/Lieut JF DENNIS MC to be made Lieutenant 25/4/18.
1/6th Battalion War Diary [WO/95/2694]
Fourteen Patrols were out, five of which were by day light
One of the latter was a bold reconnaissance of area X.16.c.60.65. This patrol went out twice during the morning and once during the afternoon, when the Officer was killed by a bullet from house X.16.c.60.65. His body could not be recovered owing to heavy rifle fire.
The Officer in question would appear to be Arthur James Nash who is recorded as killed on the 13th June 1918. see here
139 Infantry Brigade: Headquarters War Diary [WO95/2692]