The recruitment of volunteers from the Grand Duchy of Finland was clandestine and dominated by German-influenced circles, such as university students and the Finnish upper middle class.
[1] The recruits were most often clandestinely transported across Finland's western border via Sweden to Germany, where they were formed into the Royal Prussian 27th Jäger Battalion.
The Jäger Battalion fought in the ranks of the German Army from 1916 in the battles on the northern flank of the eastern front.
The Mannerheim side was oriented towards an alliance with Sweden, which remained neutral during the war but which was opposed to Russia, and with which Finland shared its history up to 1809.
However, the kingdom was never realized beyond this election; and when World War I ended and the German Kaiser fled, the nascent Finnish monarchy was replaced by a republic, whereupon Baron Mannerheim returned.