Gas attacks against 18th Division 1916

[Stebie9173]

Does anyone know from histories, War Diaries, etc. whether there is much mention of specific gas attacks versus the 18th Division, and specifically against 54th Brigade & the 6th Northamptonshire Regiment.

Was gas used to anyone's knowledge in counter-bombardment of the assaults on the Pommiers Redoubt area on 1st July, at Trones Wood on 14th July or at Thiepval on 26th September 1916?

Was gas ever used in "defensive" artillery fire?

I have noted that gas was used by the British at Thiepval at the culmination of the preliminary bombardment. Since the 6th Northants was in support behind the 11th Royal Fusiliers and 12th Middlesex that day, it is unlikely that many of the Northants men would have been far enough advanced to be affected by the British gas before it dispersed.

Also, there was a major German raid on 29-12-1915 which used gas specifically against the 6th Northants.

The reason I ask is that my great-uncle of the 6th Northants was "severely gassed", according to his daughter, "sometime during the war". He was not discharged unfit however and in early 1917 (I believe) he was transferred to the Royal Engineers. The "severely" part, I am taking with a pinch of salt, but it could well have prompted his change of Corps.

Since his service record was destroyed, I am attempting to narrow down possible dates to have a deeper look at events.

Thank you for any insights anyone can provide.

Steve.