For some reason which is not apparent De Wet, although he had an open country in front of him in which not a single British column was operating, moved slowly, and thereby gave more time for the carrying out of Lyttelton's arrangements. Possibly he may have been delayed by trouble with his Free State commandos, some of which a few days later refused to cross with him into the Colony. On January 31 he passed through Dewetsdorp, gratified no doubt to find that since his capture of it in November his enemies had not ventured to set foot again in it. At that time he had not made up his mind whether to cross the Orange east or west of Norval's Pont. If the former, he would soon be able to join Kritzinger, who after the Willowmore raid had returned to the Zuurberg, between Stormberg and Naauwpoort; if the latter, he would be able to call up Hertzog, who had returned from the shores of the Atlantic and was hovering in the Carnarvon district west of De Aar.
De Wet had from time to time to time been in communication with Kritzinger and Hertzog during their raids. His advanced patrols soon discovered that the section of the Orange lying eastward of Norval's Pont was very strongly held. The dispositions of Lyttelton's troops seem to have been made on the assumption that De Wet would endeavour to join Kritzinger, who was little more than one day's march from the left bank, rather than Hertzog, who was 150 miles away. The river section westward of Norval's Pont was therefore held lightly by a line of outposts at the drifts, thrown out from the main barrier based on Naauwpoort, nearly forty miles south of the river. Of this De Wet was at the time unaware. His information was that the eastward section was impassable. The westward section might possibly not be so, and he determined to make for it.
He spread a report that he intended to cross the river at Odendaalstroom or Aliwal North, and paused to allow it time to reach the ears of Knox, who seems to have given some credence to it. A column was sent out to reconnoitre in the direction of Smithfield. When half-way between that town and Dewetsdorp, De Wet suddenly changed direction and made for Phillipolis, detaching a portion of his force under Froeneman, who on February 5 captured and burnt a train a few miles south of Edenburg and crossed the railway. On the following night, De Wet crossed it with the main body near Springfontein, while Knox was hunting for him near Bethulie.
It was now evident that De Wet's objective was the Zand Drift on the Orange west of Phillipolis. He had had a long start, and the nearest troops available for the pursuit of him were the columns of Knox and Hamilton at Bethulie. Here the river bends round to the south, forming an arc through Norval's Pont towards Zand Drift; and the columns therefore crossed to the right bank and marched eighty miles along the chord, only to find when they reached the Drift on February 12 that De Wet had two days previously crossed by it into the Cape Colony.
The operations of the next sixteen days were confined to a comparatively small rectangle of about 6,000 square miles lying on the left bank of the Orange, which bounded it from Norval's Pont to Douglas and thence to near Prieska. The S.E. side and half the S.W. side, namely from Norval's Pont to Naauwpoort and thence to De Aar, were formed by the railways, the remaining portion of the S.W. side being the river Brak, which flows into the Orange a few miles above Prieska.
Owing to a sudden flood, which delayed Knox for two days, he was unable to follow De Wet across Zand Drift, but Plumer started from Naauwpoort with two columns, and on February 12 came in touch with De Wet and compelled him to change his course. Two days later De Wet crossed the railway between De Aar and Hopetown, after a rearguard action with Plumer, into whose hands fell next morning the transport which De Wet had been compelled by bad weather to leave behind him.
De Wet now proposed to fetch a compass towards Prieska, where he hoped to effect a junction with Hertzog, but the driving power of the raid was slowly exhausting itself. The motive energy was stored up in accumulators, and when these were discharged in succession, there was no means of re-charging them. Hertzog and Kritzinger, who had been relied on for this purpose, were not at hand; more than a third of the force with which De Wet had originally left the Doornberg had declined to leave the Free State; and the transport had been lost.
Plumer also was exhausted and unable to continue the pursuit, but fortunately Knox was close behind him. He doubled back towards Hopetown for supplies, leaving Knox to follow the trail. De Wet was now driven into the western corner of the rectangle where the Brak falls into the Orange, and where he found himself in a dilemma similar to that which in his first raid had cornered him between the Orange and the Caledon. The Brak was in spate, and he could not cross it to Prieska. All hope of joining Hertzog and of a successful raid into the Cape Colony was at an end; there was nothing to be done but make the best of his way back to the Free State. He reversed his course and made for the confluence of the Orange and the Vaal. His change of direction was not known to Knox, who, assuming that De Wet must have crossed the Brak, which fell as suddenly as it had risen, threw his columns across it and trekked for twenty miles towards the S.W. Hertzog was reported to be a day's march higher up the Brak.
Up to this time the whole of the stress of the pursuit had fallen upon Knox and Plumer. As soon as the news of De Wet's entry into the Cape Colony reached Lord Kitchener, he hurried down from the Transvaal to De Aar to superintend the casting of the nets. His first dispositions were made with the object of preventing De Wet and Hertzog breaking away into the districts lying west of the railway to Capetown, and an ingenious and elaborate scheme of columns springing out from the line in succession from the north, was arranged. It was not, however, put into action, for Knox and Plumer had headed back De Wet, and for the time being had prevented a junction between him and Hertzog. It was no longer a case of a stern chase, but of the fencing in of a comparatively limited area, into which more than a dozen columns were thrown, and which by February 24 was reduced to the district bounded on three sides by the railways and on the fourth by the Orange.