The Germans had withdrawn to the Hindenberg Line in Feb 1917, and the British had constructed defensive positions opposite the Hindenberg Line. The 1st and 2nd Dublins, plus the 10th Dublins remnents in 19th Entranching Battalion and 8/9 Dublins in 20th Entrenching Battalion were north on St Quentin
The Dublins were in the sector north of St Quentin The 1st and 2nd Battalions were holding a section of the line near the village of Epehy. The 10 Dublins were a part of 19th Entrenching Battalion, making up about half the manpower of this entrenching battalion
The map below shows the movements of 19th Entrenching, but further information is hard to find.
Royal Dublin Fusiliers