Martti Aho participated in the Finnish Civil War in 1918 and in the Aunus expedition of 1919–1920.

Due to his skilled command, during the Army of Karelia's breakthrough and the conquest of Petrozavodsk, Aho was rewarded the Mannerheim Cross on 1 March 1942 as knight number 52.

During the stationary phase of the war, Aho was stationed at the Svir River with his regiment.

During the great Soviet offensive the 11th Division was transferred to the Karelian isthmus, where Aho and his regiment participated in the battle of Tali-Ihantala from 27 June.

During the Lapland War, JR 50 participated successfully as part of Ryhmä Pajari, fighting the Germans north of Tornio.