The Finnish 27th Jäger Battalion (German: Königlich Preussisches Jägerbataillon Nr. 27) was an elite light infantry unit in the German Army from 1915–1918 which consisted mainly of volunteers of Finnish Jäger troops.
The recruitment of the Jäger volunteers from the Russian Grand Duchy of Finland had to be secret, and was dominated by German-influenced circles, such as university students and the upper middle class. The recruitment was however in no way exclusive. The recruits were transported across Finland's western border via Sweden to Germany, where the volunteers were formed into the Royal Prussian 27th Jäger Battalion. It was a continuation and expansion of the "Boy Scout Training" (Pfadfinderkursus).
Later, the Pfadfinderkursus received more permanent forms and the course was changed into a permanent training group in Lockstedt, the Ausbildungs-Truppe-Lockstedt, which had given military training to Finnish volunteers eager to fight for independence.
More than 200 university students had participated in the so-called Boy Scout training – they dressed in Boy Scout uniforms during training, and they became the officers of the Finnish Jäger Troops. This group was expanded by extensive recruitment in the autumn of 1915 and spring of 1916. The goal was to increase the unit to 1,200 men, including artillery and pioneers. As the new recruits included working class young men and farmers as well as sailors, not so many of them knew German. It was therefore necessary to create military guide books in Finnish, and a command vocabulary was created.