Tamm was born in Stockholm, Sweden, the son of the bank director and later finance minister Henric Tamm and his wife Louise Tham. He became a second lieutenant at the Svea Life Guards in 1916 and was promoted to lieutenant in 1919. Tamm attended the Royal Swedish Army Staff College from 1925 to 1927 and became captain of the General Staff in 1930 and at the Svea Life Guards in 1934. He entered the Ethiopian Empire service in 1934. Captain Tamm and the then Chief of Air Force, Major GeneralEric Virgin, who was employed as the emperor's military political adviser, as well as four other military officers entered together into the Ethiopian service to organize the country's only military school for the training of Ethiopian officers. A Swedish military academy for cadets was established in Holeta Genet under captain Tamm who, with his staff, stayed on in Ethiopia after the outbreak of the Second Italo-Ethiopian War despite pressure by the Swedish government to return. Tamm re-entered into the Swedish Army as captain of the General Staff in 1936 and was a teacher of tactics at the Royal Swedish Army Staff College in 1936. Tamm became major in the General Staff Corps in 1937 and was promoted to Lieutenant Colonel in 1939. During World War II, he was a member of the Finlandskommittén and in 1940 he entered into Finnish service and became commander of the II. Battlegroup of the Swedish Volunteer Corps during the Winter War. He was a lieutenant colonel of the General Staff Corps and head of department at the Army Staff's Education Department in 1940. Tamm was colonel in the General Staff Corps in 1941 and head of the Royal Swedish Army Staff College in 1941 and commander of the Southern Scanian Infantry Regiment from 1942 to 1944. Furthermore Tamm was Inspector of the Infantry from 1944 to 1946 and was back again in Ethiopian service from 1945 to 1946. He was deputy military commander of the I Military District in 1946 and was promoted to major general and was Chief of the Army Staff and the General Staff Corps from 1948 to 1953. Tamm was military commander of the I. Military District from 1953 to 1961 and was inspector of Kristianstad Higher General Secondary School from 1953 to 1958. He was promoted to lieutenant general in 1961.
Personal life
Tamm married for the first time in 1919 with Katarina Lagercrantz, the daughter of the envoy Herman Lagercrantz and Hedvig. He married a second time in 1938 with Suzanne Kartavtzeff, the daughter of the captain Wsevolod Kartavtzeff and Marta von Haartman. Tamm was the father of Annika, Per-Henric, Hedvig and Kristina. Tamm died in 1975 and was buried at Film Cemetery in Östhammar Municipality.
