The third shell hit the ship shortly after 18:00; this projectile struck the upper edge of the belt on the starboard side; since the belt had only been designed to defeat German shells, the much more powerful British shell easily perforated it. The shell then passed through the handling room for the starboard secondary turret No. III, igniting propellant charges and detonating a pair of 130 mm shells as it did so. The 15 in round then penetrated an internal bulkhead and exploded in the medical storage room. The blast caused extensive internal damage, allowing smoke from the ammunition fire to enter the machinery spaces, which had to be abandoned, though debris from the explosion had jammed the armored doors shut. Only a dozen men were able to escape using a ladder at the forward end of the room. The fourth shell struck the belt aft of the third hit and at the waterline. It also defeated the belt and the torpedo bulkhead and then exploded in boiler room 2, causing extensive damage to the propulsion machinery. "Dunkerque" rapidly lost speed and then all electrical power; unable to get underway or further resist the British ships, "Dunkerque" was beached on the other side of Mers-el-Kébir roadstead to prevent her from being sunk.