The late 19th Century was witness to a frantic global arms race; the introduction of the Mle. 1886 Lebel by the French had, almost overnight, obsoleted every other military rifle in the world. The Germans responded by fielding the Gew. 1888 "Commission Rifle", so called because it was designed by a committee, rather than any independent factory. Mauser, feeling snubbed, set to work designing a rifle that eclipsed the Gew. 88 in every way, and shopped it to the Belgians. Due to the fact that the Mauser works were running nearly at capacity supplying the Turks, Ludwig Loewe & Co. (the owners of Mauser) and the Belgian State arms factory at Liege formed a new syndicate, known as Fabrique Nationale d'Armes de Guerre (now known universally as "FN") to manufacture the new rifle. The design was wildly successful and, in 1891 Argentina, who had completed their transition to Remington Rolling Blocks only 11 years earlier, purchased an improved version: the Modelo 1891 rifle, in 7.65x53mm (a caliber now known as "7.65 Argentine.")
The new rifle incorporated a couple of significant advances: First, the bolt was a strong, one-piece unit with dual horizontally-opposed locking lugs at the front, and second, it operated from a box magazine that was loaded from stripper clips (a design first) and unlike most every other military rifle of the day, it had no magazine cutoff; it was intended entirely to be used as a fast-reloading repeater, rather than as a single shot rifle with a magazine held in reserve for "emergencies".
The action, with its dual locking lugs and push-feed, pivoting-extractor design, would be familiar to anyone owning a modern sporting rifle from Remington, Savage, or Winchester, being much closer in mechanics and operation to these current rifles than its later, claw-extractor controlled-feed brethren from Mauser.
The rimless cartidge specified by the Belgians, and known (inexplicably) to posterity as the 7.65 Argentine, is modern looking, and a close ballistic cousin to the .308 Winchester/7.62x51 NATO, throwing a 174- or 155-gr bullet at 2460 or 2710 feet per second in its military guise. Commercial hunting ammo is still available from Norma.
Possibly the most fascinating thing about the rifle, aside from how teriffically modern it appears compared to designs only a few years older, is the fact that, due to its age, it's not considered to be a firearm by the BATF. The example in the photos, built by DWM in Berlin, is remarkably well-preserved for being such a senior citizen, and is still just as fine a rifle today as it was when it was made; maybe a finer rifle now, since the meticulous craftsmanship and all-machined-steel construction harken back to a bygone era. The BATF may think it to be the last antique rifle, but thousands of shooters know better; it's really the first modern rifle.