Published in February 1917 in a secret edition strictly limited to 700 copies on security grounds, this immensely detailed manual, backed up by scores of photographs, drawings, plans and diagrams, gives the reader a complete run-down on everything that British Intelligence knew about enemy Zeppelins. Based largely on the examination of two sister 'super Zeppelins' - L31 and L33 - shot down over England, the book has chapters on evolving Zeppelin types, training and personnel; the building of Zeppelins; and their machinery and propellors; Fabric and hydrogen gas valves; bomb dropping gear; wireless telegraph apparatus; bombs, flares, guns and ammunition; bomb and machine gun sights; compasses, lifeboats, fire extinguishers and other safety equipment; and weather conditions. Although the loss of life and material damage inflicted by the Zeppelins was quite light, as a psychological weapon their effect was profound and induced near-panic, , particularly as Britain had at first no answer to them. Gradually, however, blackouts were introduced, along with searchlights ringing London and squadrons briefed to intercept and shoot down the gigantic airships. The war against the Zeppelin would be won, but before they gave way to bombers the 'Zepp' had left an indelible mark on aviation history.