On 21st September...
...1918 the 1st Royal Berkshire war diary entry reads:
At 11pm the Battn advanced their line to a depth of 600 yards. For details of attack see Battn Order No 11. (Artillery Barrage attached)
France, REF MAP 51B NW 1/20,000 & OPPY 51B NW2 1/10,000