The Jääkäri troops were initially Finnish volunteers served with the Germans, training as Jägers (elite light infantry), during World War I as the Royal Prussian 27th Jäger Battalion. They fought on the northern flank of the eastern front from 1916. The Finns were secretly recruited from university students and the upper middle class, though other member of Finnish society were also recruited.
At the outbreak of the Civil War in Finland
Jägers who intended to engage on the “White” (non-Socialist) side in the
war were released from German service. 2,000 volunteers were soon
fighting to put down the communists.
Their contribution to the White victory and Finnish independence was
critical. They provided crucial leadership and training to the mostly
green troops of the Civil War.
Immediately after the Civil War, they were
afforded the right to use the word Jääkäri in their military ranks. Many
of the Jääkäri continued their military careers, and the Jääkäri units
continued in service as Finland’s elite. During the 1920s there was some
tension between the German trained Jääkäri officers and those who had
served with the Russian Imperial army. By the Winter War most of the
commanders of army corps, divisions and regiments were former Jääkäri.