Hi,
The watch is made by the General Watch Co/Helvetia.
Have a look at my site here for more info.
https://www.helvetiahistory.co.uk/trench-watches
The hallmark dates it to 1909 which is nice and early. It's actually useful for me as at the moment my serial number lookup only goes back to 1914 at about 2,880,000 so knowing 2,670,000 is 1909 is very handy.
Below is an advert with a version of the movement from 1927.
View attachment 1175103
Thanks. Carl.
Click to expand...