Ridge was quarried up until 1914 when at the start of the First World War, Ridge was requisitioned by the War Department. They cleared out the waste stone and stacked it up in older parts of the workings and strengthened the roof so that ammunition could be stored in the mine.
During the build up to WW2 the War Department decided that there was a need for a large underground ammunitions store. It was decided that the required space could be obtained by converting four quarries, these four formed what was collectively known as Central Ammunitions Depot Corsham.