Candidates: 1. Dog, 2. Horse, 3. Mule, 4. Pigeon , 5. Man, 6. Microbe, 7. Other ... and the winner of the title 'Animal that saved the most lives in World War I ' is ...
Master of submarine warfare, scourge of German U-boats throughout the Great War from Heligoland Bight, Dandanelles, Cuxhaven, to Ostend and Zeebrugge operations in 1918.
German, Belgian, French, British, Austro-Hungarian, and Russian armies used war-dogs in the Great War as sentry dogs, scout dogs, casualty dogs, explosives dogs, ratters, and mascots etc. Heroes all!
From contemporary accounts of actions fought by the Gordon Highlanders during the first years of World War 1 (Great War, WWI, European War).
From contemporary accounts of actions fought by the Royal Welsh Fusiliers during the first years of World War 1 (Great War, WWI, European War).
From contemporary accounts of actions fought by the Coldstream Guards during the first years of the Great War (WWI, European War).
Royal Engineers Balloon Section, Kites, Heavier than Air, Royal Flying Corps, Naval Wing, Army Wing, Central Flying School, British Air Forces to 1914.
From the age of ballooning to the Great War aeronaut uniforms needed to be utilitarian in the new age of machine warfare. The Military + Naval Wings Royal Flying Corps each had their own requirements.