A group of
Australian infantry wearing Small Box Respirators (SBRs) at the
Third Battle of Ypres in September 1917. After the introduction of
poison gas in World War I, countermeasures were developed. SBRs represented the pinnacle of
gas mask development during the war, a mouthpiece connected via a hose to a box
filter (hanging around the wearer's neck in this picture), which in turn contained granules of chemicals that neutralised the gas. The SBR was the prized possession of the ordinary infantryman; when the British were forced to retreat during the
German Spring Offensive of 1918, it was found that while some troops had discarded their
rifles, hardly any had left behind their respirators.
Photo credit: Frank Hurley