Yellow cloud north of Ypres
April 1915 saw the first use of poisoned gas on the western front, as the Germans attacked north of Ypres in their efforts to break through to the coast. This new weapon was far more successful than the German High Command had anticipated, with the French 87th Territorial Division in particular sent reeling as men fled from this 'choking horror'. Some introductory historical information on Second Ypres can be found here and here.
This fictional scenario is set in the days that followed that first attack. Both sides face each other from hastily dug entrenchments, with no wire for further protection (such has been the speed of the advance the day before), and the German High Command determined to continue with its offensive: they must break through and reach the Channel.
Both armies sit astride a canal, with the British holding the nearest bridge, but having been forced off the high ground that would have protected it, towards the end of fighting the day before. The German command sees the need to take the bridge, and the commanding high ground beyond, as a platform for its next major push.
The British divisional commander fears that his troops too will be subject to more gas attacks, and his troops are fearful as they recall the tales of terror, and the sorry sights of troops stumbling from the battlefield suffering from exposure to the deadly chlorine gas.
Orders of Battle