It was in the Orange Free State and the Transvaal that the Boers displayed their greatest activity in the way of railway destruction. At Norval's Pont and Bethulie they broke down the bridges crossing the Orange River, which divided Cape Colony from the Orange Free State. Before leaving Bloemfontein (occupied by the British March 13, 1900), they destroyed all the bridges and all the culverts on the railway in their rear; they blew up miles of the permanent way, and they left the railway itself an almost complete wreck. North of Bloemfontein they pursued similar tactics along 180 miles of track, on which they wrecked more or less completely no fewer than fifty bridges, including the one over the Vaal River--a high structure with seven spans each of 130 feet. No sooner, too, had the line been reopened as far as Johannesburg than Commandant De Wet made a raid on it and undid all that the repairing parties had done over a length of thirty miles. Speedily following the re-establishing of rail communication with Pretoria, the Boers began a fresh series of guerilla attacks on the lines both in the Transvaal and in the Orange Free State; and they continued these attacks for months--until, in fact, their power for doing further mischief had been finally checked. In carrying out repairs and reconstruction work of such vital importance to the advance and security of the British forces, the policy adopted by the Director of Railways was that of employing Royal Engineers to do rapid temporary repairs--with a view to having a line of some sort made available with the least possible delay--and leaving permanent or even semi-permanent repairs to the Railway Pioneer Regiment. At convenient sidings on the railways throughout the theatre of war _construction trains_ were stationed in charge of permanent-way inspectors and sections of Royal Engineers who had at their disposal, at each of such sidings, a gang of men--whites and natives--varying in number from 300 to 1,000, according to circumstances. Infantry working-parties were also obtained wherever possible. Gangers began a patrol of the lines at dawn. Information as to any break or alarm was communicated to the nearest military post and telegraphed to the Deputy-Superintendent of Works, who thereupon ordered the dispatch of a construction train to the scene of any reported or prospective break without waiting for confirmation of the news received or of the suspicions aroused.