On the night of the January 23 Spion Kop was held as an observation post by a party of seventy burghers. When Buller first appeared at Potgieter's Drift, it was on the right of the Boer line, but now it was only the right of the centre under Schalk Burger. Little was known of its features and tactical value, beyond the information obtainable by a telescopic reconnaissance. It was a prominent object in the Boer position, and it seemed to be within the grasp of a night adventure. Woodgate left his rendezvous at 9 p.m., but it is doubtful whether he would have reached the summit before daybreak but for Thorneycroft, who was in command of the mounted infantry which bore his name, and who had before nightfall picked out and noted the recognizable objects on the slope. A staff officer from Head Quarters, who accompanied the column to direct the march, had had no opportunity of making himself acquainted with the way of access to Spion Kop, and Thorneycroft was ordered to act as guide. [Illustration: Sketch Plan of Spion Kop.] The summit, but fortunately little more than the summit, was veiled in mist, and the crest was reached. Bayonets were fixed before the Boer picket was alarmed and opened fire, but the ammunition was spent without effect, as Thorneycroft's men had by order thrown themselves on the ground as soon as they were discovered. A charge into the mist drove back the picket and scared the main body off the summit. Thus before dawn on January 24, Warren was in possession of the hill which was believed to be the key of the Boer position, and the chief obstacle in the way of his advance seemed to be thrust aside: but the mist on Spion Kop was the forecast of the Fog of War which was soon to envelope him. Woodgate, having the men, the tools and the ground, at once began impulsively to dig, without endeavouring to inform himself of the features of the position he had so easily won. A sort of a trench had been scratched on the summit by the weary men, when the mist rolling away for a little while disclosed the startling topography of the position. The surface of the plateau sloped gently at first, and then abruptly fell away, and the trench was found to be of little use. The enemy could approach on dead ground to within two hundred yards of it. Woodgate, seeing that the real defensible line was not the highest part of the summit, but the edge lower down, where the steep descent began, sent working parties to the front, but they at once came under fire. Soon the mist again enveloped the hill, and having disposed his force, he reported to Warren that he had established himself on Spion Kop.