This is my great grandfather's Elgin pocketwatch circa 1917. My dad gave it to me when I took an interest in watch repair and I repaired this from a slightly rusted and non-working state to at the very least able to run, but the time keeping is not great. It is losing ~50s a day, amplitude is 310*, and beat error is 5.5. I'm not at the point where I feel comfortable messing with the balance and regulating the pocket watch. I am just happy that it runs. I don't have a before picture, but I cleaned up a lot of green rust from part of the dial and case where there was a crack in the crystal and water must have gotten in. I replaced the mainspring because it was domed like an ice cream cone and gave all the parts a nice cleaning and lubricating.
He did serve in WWI in the 307th, but I lean towards thinking that this was waiting for him at home because the condition it was in was pretty good given the age. I also have his WWI map which he did have with him while he was in France, and I display together with the pocketwatch.