To answer your original question as to what the 1st Royal Dublin Fusiliers were doing that day, they had been through hell and back over the previous 7 days.
Only 45 men were left out of the battalion that had started the week
There is a full account here Because of the difficulties in maintaining records over the retreat, there is doubt as to which day any one man died. Basically it could have been at any point in the retreat. The fact that he appears to have no known grave and is on the Pozieres Memorial seems to indicate that he died at some point during the retreat, but it is not known where or when
