World War 1
Worldwar1.com: Trenches on the Web: The Second Battle of Ypres, April 1915
Freshly trained Canadian troops arrived at a quiet front on April 17, 1915. Five days later the Germans attacked with 5700 cylinders of chlorine gas and heavy artillery bombardment.
BBC
Bbc History: World Wars: World War One: Daily Mirror Headlines: Ypres
Collection of excerpted headlines and news reports published in the "Daily Mirror" on April 23 and 24, 1915, relates events of the fighting at Ypres, including the German use of poison gas.