It looks like it is a copy of an old S&W breaktop (Model 3?) made in Belgium. It was not a military pistol because neither the U.S. nor any other country used the .44-40 (aka .44 WCF) as a military revolver cartridge.
In good shape it should be shootable, but it was probably made in the black powder era so either use light "cowboy" loads or reload for black powder or the equivalent.
Value? Hard to say, but not very valuable. In functional condition, it might bring $200 or so from someone interested in large caliber European revolvers.