Chemical weapons in World War I in Palestine during the Second Battle of Gaza. Russia began manufacturing chlorine gas in 1916, with phosgene being produced later in the year. Most of the manufactured gas was never used. The British Army first used mustard gas in November 1917 at Cambrai, after their armies had captured a stockpile of German mustard gas shells. It took the British more than a year to develop their own mustard gas weapon, with production of the chemicals centred on Avonmouth Docks. (The only option available to the British was the Despretz–Niemann–Guthrie process). This was used first in September 1918 during the breaking
Action of 25 September 1917 the night. An intelligence summary of the Second Army assessed the German artillery in support of the of 25 September, to have been the greatest concentration of artillery on a German divisional sector ever known and was nearly four times the usual quantity for a division. The attacking battalions had assembled during the night of covered by parties of the line-holding battalions opposite the 33rd Division. The great mass of German artillery began a bombardment at but fell short and German infantry fired red flares to signal to the German artillery that they were falling short, especially on the III