Buller, having selected the route which seemed at the time to be the line of least resistance, began on January 9 to transfer the bulk of his force from Frere to Springfield, a distance of sixteen miles, but owing to difficulties of transport and the necessity of accumulating a large stock of supplies at the new base, it was six days before the concentration was effected. One brigade was left at Chieveley to watch the Boer front at Colenso. In Orders issued at Frere on January 9, Buller announced that he "proposed to effect the passage of the Tugela in the neighbourhood of Potgieter's Drift, with a view to the relief of Ladysmith." His scheme was based upon imperfect information and misleading maps, and was in fact not so much a surprise flank attack, as all his movements had to be made in full view of the enemy, as an attack from a position higher up the river that must be frontal, because the enemy would have ample time to make it so: and herein lay its weakness. When, however, he personally surveyed the situation from Mount Alice, which overlooks Potgieter's Drift, the aspect of the curving amphitheatre showed the danger of attempting to force the river at that point. On the N.E. was Vaalkrantz and Doornkop, and the high ridge of Brakfontein, which the enemy had already begun to entrench, and over which passed the road by which he proposed to reach Ladysmith, everywhere commanded by the heights, filled the quadrant towards Spion Kop on the N.W. On January 13, Buller reported to the War Office that, having found the Potgieter's Drift scheme impracticable, he proposed as "the only possible chance for Ladysmith" to send Warren across at Trickhardt's Drift, five miles higher up the river. The new scheme was based upon a theory which had been evolved out of the experiences of autumn manoeuvre battles collated on the office desks of Pall Mall, that the easiest method of defeating the enemy with a small casualty list was to contain his front and attack one or both of his flanks; and General Officers had come to regard this as the regulation opening to which they were bound to conform. [Illustration: Spion Kop and Vaal Krantz positions. _Stanford's Geog'l: Estab't._] Buller divided his force into two unequal portions. Warren with the stronger portion was to attack the Boer right which Buller believed to be weak, while Lyttelton with the remainder demonstrated at Potgieter's Drift. To himself Buller reserved the part of the Chorus in a Greek play, taking a general interest in the action, yet not personally concerned in it; and in that capacity he issued a stirring appeal to the relieving force. On January 15 "secret instructions" were given to Warren. He was recommended, after crossing the Tugela at Trickhardt's Drift, to proceed west of Spion Kop, and to pivot his right and swing round on to the open plain in rear of the Boer position facing Potgieter's Drift.