[1] The German army used poison gas, in the form of chlorine, for the first time against Triple Entente troops at the Second Battle of Ypres, Belgium, on 22 April 1915.

[3] This was followed by the Black Veil Respirator, invented by John Scott Haldane, which began to be issued to troops on 20 May 1915.

[5] It was also of fragile construction, required training to use and largely immobilised men during a gas attack as they were concerned about their mask coming loose.

[6] Seeking to improve on the Black Veil Respirator, Newfoundland physician Col. Dr. Cluny Macpherson, serving as Principal Medical Officer for the Royal Newfoundland Regiment created a mask from chemical absorbing fabric which fitted over the head.

[7] MacPherson had seen a German soldier putting a bag over his head after a gas attack and sought to replicate the design.