(Picture from the National Archives and Records Administration)
At the beginning of the war, Germany had the most advanced chemical industry in the world, accounting for more than 80% of the world's dye and chemical production. Although the use of poison gas had been banned in the Hague Conventions of 1899 and 1907, Germany turned to this industry for what it hoped would be a decisive weapon to break the deadlock of trench warfare (Duffy). Chlorine gas was first used on the battlefield in April 1915 at the Second Battle of Ypresin Belgium.Yellow-green clouds came toward the French and had a smell similar to a mixture of pineapple and pepper (Spartacus). They thought the German were hiding behind a smokescreen, ready to attack. After they felt a burning in their chests and throats, however, they noticed they were being gassed (Spartacus). Unfortunately doctors could not find a cure. Later, mustard gas, phosgene and other gases were used (Science & Technology in World War I). Britain and France soon followed suit with their own gas weapons. The first defenses against gas were makeshift, mainly rags soaked in water or urine. Later, relatively effective gas masks were developed, and these greatly reduced the effectiveness of gas as a weapon. Although it sometimes resulted in brief tactical advantages and probably caused over 1,000,000 casualties (Duffy).