Operation Mardonius

While training with the Norwegian Independent Company 1 in England and Scotland, Max Manus and Joachim Rønneberg developed the initial draft for naval sabotage based on small magnetic limpet mines with time delay, delivered to the ship from kayaks, and using a long iron stick to place the limpet on the ship's side.

[3] The two SOE agents Max Manus and Gregers Gram were sent to Norway and parachuted into Østmarka east of Oslo on 12 March 1943.

In addition to Manus and Gram, two local resistance people, Einar Riis and Halvor Haddeland, also took part in the operation.

Another target ship, Winrich von Kniprode, was abandoned because the area was lit due to ongoing night work.

In June 1943 they were decorated with the (Norwegian) War Cross with Sword, awarded by King Haakon at a ceremony in Nethy Bridge in Scotland.