CHAPTER I PAGE The first rumours of German gas attacks--Sceptically received--First attack in 1915--Canadian pluck under gas--Nernst and Haber the inventors of German gas--The difficulties of getting practicable gases--The technic of gas attacks--A German prisoner’s account 9 CHAPTER II The first respirators--First-aid devices--The smoke helmet--Anti-gas sprayers--Their use and delicacy--The English chemists set to work--The task of training the whole army 26 CHAPTER III Popular terror of gas--Necessity for drilling and early personal experience--Sure defence from gas possible--The first gas alarms--The prussic acid scare a myth--The phosgene scare a reality--The helmet made to combat it--Necessity for renovating the helmet 42 CHAPTER IV The attack of Dec. 1915--The Allies’ good training tells--The casualties analysed--The new element of surprise--Evidences of the use of phosgene--The incident of the bulb--Improved alarms--The Strombos sirens--Accidents to the horns--The Tear Gas Shell--Its chemical analysis--Combated by anti-gas goggles--Tommies scoff at Tear Gas--The Germans make it formidable 62 CHAPTER V Summer of 1916 the highwater mark of the German gas cloud--Their improved methods--The need of speed and secrecy--Gas as a rat exterminator--Causes of Allied casualties--Germans killed with their own gas--Gas masks for horses and mules--Reduced Allied casualties--Humorous incidents 88 CHAPTER VI The last German gas cloud sent over August 1916--Its intensity--“Delayed” cases of phosgene gassing--Cigarettes as a test of gassing--Dangers of carelessness--The sprayer abandoned for Mrs. Ayrton’s fan--Responsibilities of the divisional gas office--Russian gas victims--The day of the gas cloud over 112 CHAPTER VII The rising importance of the gas shell--The variety of gases practicable with the shell--The deadly Green Cross Shell--Risks of transporting “duds” for chemical analysis--Reduced Allied casualties--German blunders in shelling tactics--Importance of universal discipline 127 CHAPTER VIII The gas-proof dugout--First-aid methods of alarm--Von Buelow improves German gas tactics--Popular errors about gas--Effectiveness of new British respirators--Vomiting gas--Germans speed up their manufacture--Gas as a neutraliser of artillery fire--As a neutraliser of work behind the trenches--Raw recruits ashamed to wear the mask--Casualties resulting 145 CHAPTER IX