Black Sea campaigns (1941–1944)
The Black Sea Campaigns were the operations of the Axis and Soviet naval forces in the Black Sea and its coastal regions during World War II between 1941 and 1944, including in support of the land forces. The Black Sea Fleet was as surprised by Operation Barbarossa as the rest of the Soviet military.
Source: Wikipedia — Black Sea campaigns (1941–1944) (CC BY-SA 4.0)