From my current reading: British Capt. Alan Hanbury-Sparrow, who served in World War I, called chemical weapons "the Devil's breath." (That would be a great title for a history of chlorine and mustard gas.) Soldiers wearing gas masks, he wrote, looked like "imbecile frogs" -- I guess especially in the green haze of chlorine.
Thomas E. Ricks covered the U.S. military for the Washington Post from 2000 through 2008.