Girard Perregaux 1st military watch in the world for the Imperial Navy in 1880

Hello. A few years ago, I was lucky enough to stumble upon a watch that no one else wanted; it was completely caked in mud beneath its celluloid crystal. That actually turned out to be a good thing, as the watch remained in working order once the dial and crystal were thoroughly cleaned. I have no doubt that this is an Imperial Navy watch. The case back bears the inscription “PED Patented.” The movement was subject to strict marking protocols and lacks a specific caliber number; instead, there is simply a large letter “M” in a bold serif font. The fact that radium was not applied—something not yet common practice during that era (approx. 1880–1899)—reinforces the impression that this is one of the earliest wristwatches. Another detail: the strap appears to be original and shares characteristics with the one shown in the photo on your website. The case is made of very soft silver but bears no hallmarks; the back cover simply features a large “P” (Perret & Fils?). It was originally gold-plated, though the ravages of time and poor storage conditions have taken their toll. Otherwise, there is absolutely no record of repairs anywhere. It is an exceptionally rare piece—a veritable time capsule. And the watch actually runs; I cannot vouch for its precision, but the fact that it works at all—given the condition I found it in—strikes me as a minor miracle. Could you take a look at the photos and try to estimate whether this is truly an experimental naval series from GP, or merely a cheaper version intended for the regular crew? Thank you, and have a wonderful day. Jan.