 During the Second Boer War, in 1900, the caves were used by the Boers to store ammunition for their 94-pounder Long Tom guns.It was thought that the caves may have been used by President Paul Kruger to store the legendary "Kruger Millions", gold bullion which reputedly disappeared somewhere between Waterval Onder and Nelspruit during Paul Kruger's flight from Pretoria to Lourenço Marques (now Maputo) in Mozambique.In 1914 a company was formed to excavate huge amounts of bat guano; this was sold as fertilizer to farmers.