Lord Roberts had, however, two years before drawn up a scheme for an advance on the Transvaal by way of the Kimberley line as far as Mafeking and thence across country to Pretoria, and before leaving England he modified it so as to adapt it to action in the Free State. He proposed to leave the Kimberley line at some point between the Orange River and the Modder River, and to march in a S.E. direction on the Bloemfontein line. He was a firm believer in the indirect results of military movements, and he expected that his arrival at Springfontein or Edenburg and the menace to the Free State capital "must draw the Free Staters back from Kimberley and Natal," and that the occupation of it "would render the Boer positions south of the Orange River untenable." The official plan of an advance from the centre would force back the Free Staters engaged in the Cape Colony, and instead of isolating them would enable them to reinforce Cronje. After his arrival at Capetown, circumstances however compelled Lord Roberts to modify his plan of campaign. The news of the Spion Kop affair, anxiety on account of Kimberley, the presence of Cronje at Magersfontein and other considerations, determined him to march through the Free State by a more northerly route which would enable him to relieve Kimberley _en passant_ and to give battle to Cronje. The secret of the plan, which was known only to Lord Roberts' personal staff, was well kept, and operations were continued without reference to it. The earlier orders issued by him seemed to indicate that the central advance was still to be carried out. The VIth Division under Kelly-Kenny was sent to Naauwpoort; French was instructed to make a demonstration against Norval's Pont; and Methuen was warned that it might be necessary to withdraw part of the Modder River force. The Boers, who had captured at Dundee some intelligence papers which disclosed the original plan of campaign, were now more than ever convinced that the British Army must advance by way of Norval's Pont and Bethulie, and did not discover their error until it was too late to rectify it.[34] When Lord Roberts had made all his preparations, which involved the entire reorganization of the transport, and the raising of a considerable force of mounted troops, for his march of 100 miles across the veld eastward from the railway, the secret was disclosed to Kelly-Kenny and French on February 1. This plan of a flank march had also suggested itself to Buller, who proposed it in a memorandum which Lord Roberts found on his arrival in Capetown; but as Buller's scheme included the construction of a railway across the veld, and limited the advance of the Army to the rate at which the line could be pushed forward, it did not fall in with Lord Roberts' ideas.