Few people relied on wristwatches more than the aviators who flew with the fledgling US Air Force during World War One.  They needed to know not only know how far and fast they were flying but how much fuel remained to get them back home. This is why when the US Signals Corps received its first order of wristwatches from prestigious Swiss makers that included Omega, Ulysses Nardin, Moser, Zenith and Cyma the flyers of the Aviation Section had first claim on them.  These were among the first watches issued by any US military service and would have been essential for logging the time of messages as well as navigation.  When the war ended many of these precious objects found their way into private hands.  I don't know the history of this particular watch but the story is on the white enamel dial in the form of the luminous Arabic 24 hour digits, inner ring of 24 hour "military" numbers and the words Signal Corps U.S.A.  

I have only seen a couple of other examples of the Cyma, far fewer than Omegas or Zeniths.  The case is 35mm and appears to be silver although the only marking is a serial number.  It has a tight press on hinged back and a dust cover protecting the 15 jewel Cyma movement.  A previous owner tried his or her hand at engraving flowers on the casebook but fortunately gave up before they had got too far.  See pictures for condition but this watch appears to have been well looked after.  I have seen very few enamel trench watch dials in such good condition with the luminous numbers essential for night flying intact.  Unfortunately I cannot guarantee reliability or timekeeping on account of its age so please bear this in mind. This is a rare watch - don't let it get away. 

Overseas buyers please use the global shipping programme or contact me to arrange delivery.  Thanks, Simon