Whilst all these arrangements in regard to operation and transport were thus being perfected, the need had arisen for an equally complete organisation in another direction, that, namely, of providing for the _repair or restoration of railway lines_ damaged or destroyed by the enemy. Since the American Civil War the art of railway demolition had made considerable advance by reason of the use for this purpose of dynamite--an agency which was now to be employed very freely by the Boers. With dynamite they easily blew up the bridges, or material portions thereof; they destroyed the track for considerable distances by the simple process of exploding dynamite cartridges under alternate rail-joints; they wrecked culverts, pumps and water tanks, and they effectively damaged locomotives which they had not time or opportunity to remove. Then, among other things, they derailed engines and trucks by means of mines; they caused obstructions by throwing down into the railway cuttings boulders of up to two or three tons in weight; they cut telegraph lines; they removed or smashed up instruments and batteries at railway stations; they wrecked the stations; they burned many railway trucks, or otherwise rendered them useless; they set fire to stacks of fuel, and, when dynamite cartridges were not available, they deprived the locomotives of their vital parts and tore up considerable lengths of rails. By December, 1899, it had become evident that the Railway Companies and the Fortress Companies of the Royal Engineers, sent out to the Cape and brought up to their fullest strength, would be unequal to the requirements of the prospective situation. The Railway Corps thus formed was, accordingly, augmented by a Railway Pioneer Regiment, composed of miners, artisans and labourers who had been employed at Cape Town or Johannesburg, volunteers from the ranks of the Army (preference being given to those already possessed of experience in railway work), and employés of the Orange Free State Railway. Some Field Railway Sections, created to form the nucleus of a staff to take over the working of railways in the enemy's country became construction parties, doing repairs only, and having no control of traffic except at railhead. In addition to all these, a large number of natives were engaged through Native Labour Depôts opened at De Aar, Bloemfontein and Johannesburg, the number so employed at any one time attaining a maximum of about 20,000.