Gas masks. British soldier and a horse wearing gas masks during the World War I (1914-1918). The masks included eye protection, and used charcoal in a container to absorbed the gas from the air. Earlier models were just flannel masks soaked in urine or soda. Chemical weapons were first used by Germany on April 22nd, 1915, when chlorine gas was released from cylinders on the western front at Ypres in Belgium.