This popped up on ebay last week as a £50.00 buy it now
During the Great war the British military had been issuing pocket watches to serving personnel and hadn't supplied wristwatches, these where instead bought mainly by officers privately for use at the front lines with wristwatches improving and the introduction of the water resistant cases, unbreakable crystals and radium dials the Trench watch was born and became an item of necessity for serving personnel.
It wasn't until 1917 that the war department purchased the first batches of wristwatches supplied in two forms the first being a classic trench watch of water resistant case, black dial with radium numerals and unbreakable crystal and the second type being a large cased snap back, black dial with radium numerals all had 15 jewel Swiss movements. These watches where purchased for the purpose of evaluation to assess the usefulness of issuing wristwatches to serving personnel.
This watch is of the snap back type and has a unusually large for the period 38mm case made of nickle, the dial is black enamel with radium numerals.
All the snap back models have issue numbers that follow the same form a five digit number beginning with a nine followed by a letter M there is also a Broad arrow mark or Pheon crudely stamped on to the back some watches are stamped with two broad arrow marks that touch at the tip this is thought to indicate that the watch had been withdraw from service.
The movement in these large snap back models is the same in all known watches where as in the water resistant 1917 watches there is some variation. The movement is a good quality 15 jewel movement and no one has yet been able to identify who manufactured them there are no identifying marks but there is a brevet patent number on the dial side so it may be possible to trace that and establish who made the movements.
No one is sure what branch of the armed forces these snap back watches where issued to but it cant have been to front line personnel because having no water resistance would have rendered them pretty useless in the field, many have speculated that they could have been issued to the flying corps because the design mirrors quite closely the pocket watches already issued to them at the time, these snap back models where only issued in 1917 and withdraw from service shortly after, but the water resistant watch became a regular issue watch there after
It is however an interesting footnote in the development of the military wristwatch and is amongst the first officially issued and stamped British military watches of the Great War.