On 15 May four ships; the fleet tender Grille with the staff of FdU Norwegen on board, the fleet oiler Kärnten, and the depot ships Huascaran and Stella Polaris, and fifteen U-boats including U-481, sailed for Trondheim, but were intercepted after two days by the Royal Navy's 9th Escort Group and officially capitulated.
On 15 May four ships; the fleet tender Grille carrying FdU Norwegen's staff, the fleet oiler Kärnten, and the depot ships Huascaran and Stella Polaris, along with fifteen U-boats including U-481, set sail for Trondheim. However, after two days, they were intercepted by the Royal Navy's 9th Escort Group and officially surrendered.