Commissioning was delayed slightly due to light damage sustained during a Royal Air Force attack on Kiel on the night of 1 July 1940. "Prinz Eugen" suffered two relatively light hits in the attack, but she was not seriously damaged and was commissioned into service on 1 August. The cruiser spent the remainder of 1940 conducting sea trials in the Baltic Sea. In early 1941, the ship's artillery crews conducted gunnery training. A short period in dry dock for final modifications and improvements followed. In April, the ship joined the newly commissioned battleship for maneuvers in the Baltic. The two ships had been selected for Operation Rheinübung, a breakout into the Atlantic to raid Allied commerce.