He was the skipper of the fishing vessel "Arthur" during an attempt to sink the German battleship "Tirpitz" in the Trondheimsfjord in the fall of 1942 (Operation Title). Despite its failure, Larsen received a Conspicuous Gallantry Medal, the first non-Briton to do so. The Admiralty records the operation as "the achievement of penetrating to within of the berth occupied by the Tirpitz represents, on the part of the personnel and particularly that of the Norwegians, a fine example of cold-blooded courage."