When we think of World War One we picture weary soldiers ‘coughing ... a dying man and almost taste the ‘green sea’ of lethal mustard gas. These vivid impressions sprang from the pen of ...

But the most infamous - and deadliest - was mustard gas, in reality an oily vapour first used by the Germans in July 1917, again near Ypres. Known as the “King of Battle Gases”, it acted by ...