During World War I, he served as a volunteer in the German light infantry, his first engagement being on the Misa River in Latvia on the eastern front in 1916.

[3] However, the parliament was often dissolved by tsarist Governors General and many Finns despaired of gaining full political rights.

[5] Groundstroem left his theological studies and joined the 27th Jäger Battalion (Finland) as a volunteer on 29 December 1915.

[1][2] The Jäger Movement consisted of Finnish volunteers who had slipped away to Germany to train as soldiers and to fight during World War I.

[2] Groundstroem was influenced by a militarism that he thought beneficial to young men, including "country boys" as well as "bookworms and spoilt, sloppy idlers".

[10] After the October Revolution in Russia, the Finnish socialists followed Vladimir Lenin's urging and on 9 November 1917 set up a Revolutionary Central Council of Workers in Helsinki.

They named Carl Gustaf Emil Mannerheim commander in chief, and he quickly took control of central and northern Finland.

[11] Groundstroem returned to Vaasa, the temporary capital of Finland in the White region, and on 25 February 1918 was promoted to lieutenant.

In March 1918 he was appointed a battalion commander in the White forces, taking part in battles in Tampere, Lahti, Lyykylä, Mannikkala and Tali, where he was slightly wounded.

[1][2] Kurkiala participated in the Winter War (November 1939 – March 1940) against the Soviet Union as pastor to the 15th Infantry Regiment, which took part in military operations in Summa.

[2] Later in 1941, Kurkiala joined the Finnish Volunteer Battalion of the Waffen-SS as its chaplain, succeeding SS-Untersturmfuhrer Ensio Pihkala, who had died.

[18] Kurkiala made a speech to the battalion on 2 June 1943 in which he accused the Prime Minister, Edwin Linkomies, of failing to provide support.

[20] After the war Kurkiala and his family moved to Sweden, where he got a job as a primary school teacher at Sunnersberg.

[2] Iivari Rämä's biography of Kalervo Groundstroem (later Kurkiala) was published in 1994, titled Jääkäripapin pitkä marssi (The Jäger Priest’s Long March).