Oskar Rantala was the regimental commander of the Helsinki Punakaartin 3.; and he was also the commander of the Eastern front. Later, at the end of the war, he led the city defense during the Battle of Vyborg together with Edvard Gylling.
Rantala was an old Punakaartin veteran, who was involved in the 1906 Sveaborg rebellion. The White Army intelligence headquarters, according to the report, he was heard during the civil war, including the Revolutionary Tribunal.