The end of the fort's active service came at 5 a.m. on 6 July 1900 when the No. 3 magazine which held 3 tons (3 tonnes) of gunpowder exploded. An inquiry found that Gunner Haines had fired a ball cartridge down a ventilator shaft causing the explosion, after being put on a charge for returning late to barracks, however this explanation has been challenged. The wall separating the fort from the moat on the south west corner was demolished and wreckage thrown up to . No one knew why the gunner had blown up the fort, but it has been speculated that it was an act of suicide. The cannons were hauled away by traction engines.