The rapid expansion of the RAF during the mid/late 1930s necessitated a massive storage requirement for high explosive bombs and other ordinance. Drawing on the experience of the Great War ammunition factories, the authorities set about identifying underground sites around Britain safe from the threat of air attack. Unfortunately in the haste of the moment safety arrangements were not a high priority and, as a result, there were a number of appalling accidents; the most serious occurred in November 1944 when 3,800 tons of HE bombs detonated at the same time resulting in the deaths of 68 people in a Staffordshire quarry.