Haraldsson was born on Munsö, Uppland, on 7 March 1919.

Before the war he lived in Järfälla and served as vicekorpral (Vice Corporal) and mechanic at F8.

During the Winter War he served as a volunteer in the Finnish infantry.

He volunteered for service Finland during the Continuation War and arrived to this country on 25 February 1942.

At first he served as a car-mechanic but was posted to LeLv 42 on 21 March 1942 as an aircraft-mechanic. During this period he also served in LeLv 46.

He was then transferred to LeLv 6.

Haraldsson was killed when Blackburn Ripon IIF RI-152 crashed 500 metres west of Nyhems lighthouse on 4 September 1942 during submarine reconnaissance over the Sea of Åland. The pilot of RI-152 was 29-year-old luutnantti Kalervo Malinen, who also was killed.

Haraldsson was together with Gustaf-Mauritz Armfelt the only foreigners that served in the Finnish Air Force during the Continuation War.

He is remembered together with Malinen on an memorial plate in a stone on the island of Nyhamn, south of Mariehamn.

Sources:
Article by Eino Ritaranta in "Suomen Ilmailuhistoriallinen Lehti" no. 1/1996 kindly provided by Carl-Fredrik Geust
De stupade svenska frivilliga i Finlands försvarskamp 1939-1944 - Armémuseum
Suomen sodissa 1939-1945 menehtyneiden tiedosto
Additional information kindly provided by Carl-Fredrik Geust and Jouko Rautio.