Vintage WWI Zenith

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Hello everyone,

I am relatively new to vintage military watches, and I came across something very interesting.
A vintage Zenith from the 1910s which was believed to be made during WWI, it was bidded up to 1300 usd on Ebay.
It appears to be in immaculate condition, possibly a NOS. I wasn't able to find something similar, but it looks very familiar to vintage longines and vintage eberhard with the same features.

Here is the link for the watch
http://www.ebay.com/itm/RARE-MILITARY-W ... 1587516721

It's quite an interesting watch, with a very special enamel dial I believe, breguet hands and the overall condition is amazing. Although the movement was not signed "Zenith", it is a Valjoux 22 GH, which was mass produced I believe.

Does anyone have specific knowledge in this field and how it actually values?