 During gunnery training on 5 May , there was a premature detonation in the left gun of <unk> 's <unk> No. 5 that disabled both guns and killed 51 crewmen . Both aft magazines were flooded to <unk> the resulting fire and save the ship . She received temporary repairs during which the turret was removed and replaced by a circular armour plate on which three triple 25 mm gun mounts were positioned . On 11 May a valve in <unk> 's No. 2 engine room stuck in the open position and flooded the engine room . While under repair at <unk> , both ships received prototype Type 21 <unk> . <unk> by Vice @-@ Admiral <unk> <unk> , the 2nd Battleship Division set sail with the <unk> Support Group on 28 May , at the same time that most of the Imperial Fleet began an attack on Midway Island ( Operation <unk> ) . 
