Three days later, on the night of 9–10 April, several British bombers dropped around of 227 kg AP bombs on the ship, four of which hit. All four hit the starboard side of the forward superstructure. Two of the bombs exploded on the main armor deck while the other two failed to detonate. The attack killed 72 initially and wounded 90, of whom 16 later died of their injuries. The bombs slightly damaged the main armor deck and caused some structural damage on the starboard side. It was decided to make alterations to the ship while she was drydocked for repairs; these included the installation of fourteen additional 2 cm anti-aircraft guns and six 53.3 cm torpedo tubes amidships. The aircraft hangar was rearranged, and the catapult that had been mounted on top of it was removed. The length of repairs and modifications precluded participation in Operation Rheinübung, the sortie by the new battleship in May 1941. The British continued to attack the ship in drydock, though no further damage was done. On 6 February 1942, a bomb fell close to "Gneisenau", but caused no damage.