Jäger (singular [der] jäger, plural [die] jäger, ˈjɛːɡɐ; "hunter") is a German military term referring to specific light infantry units.
In German-speaking states during the early modern era, the term jäger came to denote light infantrymen whose civilian occupations (mostly hunters and foresters) made them well-suited to patrolling and skirmishing, on an individual and independent basis, rather than as part of a large-scale military unit or traditional line infantry. As a consequence, jäger was used to describe skirmishers, scouts, sharpshooters and runners.
The word's usage and derivatives broadened over time. For instance, Feldjäger was the name given by the Prussian Army to scouts and runners. Conversely, in the modern German army (Bundeswehr), Feldjäger is the name given to military police.
Jäger is usually translated into English as:
"rifleman" (in an infantry role) or "Rifles" (in regimental names); and
"ranger" (especially in North American English; see below).
In English Jäger is often written as jaeger (both pl. and sgl., which is the alternative German spelling without umlaut) or anglicised as jager (pl. jagers) to avoid the umlaut completely.
According to a popular theory, the earliest known jäger unit was a company formed in about 1631 in Hesse-Kassel, under William V, Landgrave of Hesse-Kassel. Wilhelm supposedly formed an elite light infantry unit for the Hessian Army, around a core drawn from his personal staff of gamekeepers (revierjäger; "game preserve hunter"), forest rangers and professional hunters.
It was not until the first half of the 18th century that the widespread recruitment began in various German states of gamekeepers, huntsmen and foresters employed on crown estates or those of noble landowners, for specialized units of riflemen and skirmishers.
By the early 19th century, because of their civilian occupations, jäger were usually familiar with the first true rifles, rather than the muskets used by regular infantry. While early long rifles took longer to load than the smoothbore musket of the line infantry, they had greater range and accuracy.