The effective use of modern heavy field guns by the Boers during the Second Boer War (1899–1902) was a revelation to armies in Europe including the British. They were impressed by their mobility and range. Britain used some heavy guns in that war under ad hoc arrangements. After the capture of Pretoria in 1900 Lord Roberts, the commander-in-chief in South Africa (and an artillery officer), had stated the requirements of a heavy field gun: a range of 10,000 yards, weight behind the team of no more than 4 tons and the largest possible shell, accordingly the Ordnance Committee in London ordered experimental guns and three were trialled.