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 May 15th, four ships – the fleet tender Grille with FdU Norwegen’s staff aboard, the fleet oiler Kärnten, the depot ships Huascaran and Stella Polaris, and fifteen U-boats including U-481 – departed for Trondheim. Two days later, they were caught by the Royal Navy's 9th Escort Group and surrendered officially.