The Royal Gunpowder Mills were first established in Ballincollig in 1794, by Corkman, Charles Henry Leslie. He chose Ballincollig as a site for the gunpowder factory because of its proximity to Cork city, and because of the flat valley and its water-power potential. Leslie built a weir to produce a head of water and a canal, one and a half miles long which was fed by the River Lee and which powered his two mills at the eastern end of the site.