French commander Georges Lamour saw something surreal drift his way - a yellow-green cloud. 'All my trenches are choked,' he cried into the field telephone to headquarters. 'I am falling myself!' Chlorine gas — carried by favourable winds over Flanders Fields from German positions — had been used for the first time. It was April 22, 1915. Scroll down for video Chlorine gas — carried by favourable winds over Flanders Fields from German positions — sowed terror and agony for the first time on April 22, 1915. Above, German Red Cross workers carry bottles of water to help revive troops