He informed Buller of his decision, adding that certain "special arrangements" which he had made would oblige him to remain near Trickhardt's Drift, and that he must therefore have further supplies. The "special arrangements" were in fact the steps which every general would take before attacking a strong position not immediately accessible; namely to acquire ground from which it could be threatened and shelled. Clery was ordered to direct the operation, which Warren believed would entail "comparatively little loss of life." Early on January 20 Clery with one brigade and artillery advanced up the re-entrant which springs from the river towards the east end of the Rangeworthy Heights, and posted his guns half way up the valley on Three Tree Hill. Hart, with a brigade of five battalions, was sent to occupy the irregular southern crest of the heights running from Three Tree Hill towards Bastion Hill. He drove the Boers out of their advanced trenches, but found that the northern and higher crest to which they had retired, could only be won by a frontal advance across open ground. He and his brave Irishmen were as ready as ever to push on in the line of the greatest resistance, but he was ordered by Clery to forbear. Meanwhile Dundonald, not deterred by the damping of his trek on the 18th, and while obeying an order from Warren to come to heel, seized Bastion Hill, thereby securing Hart's left flank on the crest. So far as they went, the operations of January 20 were successful. Warren's pivot movement was in train, the whole of his force was now threatening the Boer right which was widely extended but deficient in depth; and the day's casualties were few. Following the example of Buller, who delegated his authority to Warren, the latter entrusted the conduct of the day's operations to Clery, who in succession ordered the chief movement to be carried out by Hart. Next day the mounted troops on Bastion Hill were relieved by infantry. Buller was aware that the Ladysmith garrison, weakened by sickness and privation, could give him little or no help; but at least during the earlier phase of the Trickhardt's Drift operations he was confident. On January 17 he told White that "somehow he thought he was going to be successful this time," and that he hoped to be within touch of Ladysmith in six days. His Head Quarters were at Spearman's Camp, a few miles south of Mount Alice, whence he rode over daily to note and criticize the tactics. It now occurred to Warren that he might have been mistaken as to the significance of the position occupied by the enemy on the Rangeworthy Heights, and that it might be in reality a screen to hide a trek of the Free Staters back to their own country; and on this supposition, which was founded upon reports that the Siege of Ladysmith had been raised and that some wagons had been seen on trek westwards towards the Drakensberg passes, he applied for reinforcements to enable him to block the way.