A Borchardt Pistol
This is one of the legendary Hugo Borchardt pistols which is credited to be the predecessor to the Luger. Many of the design features are nearly identical to those found on later Luger pistols. It's military acceptance was hindered by the 7.65 cartridge for which it was designed. Luger's redesign incorporated a 9 m/m cartridge and the rest is history as they say.
click on image to enlarge