Bay of Kotor
When the German-led Axis invasion of Yugoslavia began on 6 April 1941, she was located in the Bay of Kotor on the southern Adriatic coast along with the three other submarines of the Submarine Division. On 10 April, "Osvetnik" and "Hrabri" received orders for an operation against the Italian enclave of Zara on the Dalmatian coastline, but the mission did not proceed. On 17 April, she was captured by the Italian XVII Corps at the Bay of Kotor.