Unternehmen Donnerkeil (Operation Thunderbolt) was the codename for a German military operation of the Second World War. Donnerkeil was an air superiority operation to support the Kriegsmarine's (German Navy) Operation Cerberus, also known as the Channel Dash. During the Channel Dash the Luftwaffe defeated British air attacks on the German ships, allowing them to reach German waters. In the air battles that took place over the Channel the British suffered many losses for no return; German losses were modest and the operation achieved its objective.