[2] At the time he was also active in the Young Communist League (until 1923 the Labour Party youth wing).
[6] He was a member of the Communist resistance movement, as Norway was occupied by Nazi Germany from 1940.
[1] In the now-illegal Communist Party he was one of the leading figures together with Henry W. Kristiansen, Just Lippe, Johan Strand Johansen and Emil Løvlien.
[8] Eventually, together with Arne Gauslaa he led the party's organizational centre which had contact with communist resistance members who hid in the mountains.
[1] His brother Ivar Lie was also a communist resistance member, who managed to flee to Sweden.