Air Guns where making a name as war weapons in the time between Bow and arrow to Black powder.
They had better power than a crossbow and where quicker to reload
Black powder cut them short
I think France had some in their army
I'll Goggled and edited
In this era, France, Austria and other nations had special detachments of snipers who carried air-rifles.
The Austrian 1780 model was named "Windbüchse" (literally "wind rifle") in German. The guns were developed by the gunsmith Bartholomeo Girandoni (1744-1799), and are occasionally called "Girandoni air guns" in literature (the name is occasionally spelled "Girandony"). The Windbüchse was about 4 ft (1.2 m) long and weighed 10 pounds (4.5 kg), which was about the same size and mass as a conventional musket of the time. The reservoir was a removable, club-shaped butt; the gun was recharged by replacing the exhausted reservoir with a new one. The Windbüchse carried twenty lead balls of .52 inch caliber (13mm) in a tubular magazine. It could shoot one magazine in about thirty seconds, which was a fearsome rate of fire compared to the slow-loading muzzle loaders of the period. A shot from this gun could penetrate a one-inch wooden board at a 100 paces. The effect is roughly equal to that of a modern 9mm or .45 caliber pistol.
From: http://en.allexperts.com/e/a/ai/air_gun.htm