ABSTRACT
On the afte rnoon o f April 22 , 1915, a large volume o f com pressed chlorine, p robab ly close to 150 tons, w as released from thousands of storage cylinders in the G erm an trenches along the northern arc of the Y pres salient. W ithin m inutes, dense clouds o f the asphyxiating gas drifted w ith the wind into a four-m ile-w ide sec to r held by units o f the F rench Forty-fifth (A lgerian) and E ighty-seventh (T erritorial) D ivisions, killing som e soldiers outright, seriously incapacitating many m ore, and causing hasty w ithdraw als o f the o thers in m uch o f the affected a re a .1 A lthough a broad gap was thereby tem porarily opened in th e A llied lines, the G erm ans did no t fully exploit their advantage. By the end o f the day th e ir infantry had overrun p a r t o f the Y pres salient and cap tu red over fifty F rench and B ritish guns, bu t no strateg ically decisive breakthrough was attem pted o r ach ieved .2
