The exigences of the military situation called for the withdrawal of most of the troops operating against Kemp and Delarey in the Western Transvaal; and by the middle of September, 1901, these leaders had practically but one column to evade, namely the force formerly commanded by Dixon and now by Kekewich. He left Naauwpoort on September 13, and after some preliminary work on the Magaliesberg passed through Magato Nek, and with a force of less than 1,000 men advanced into the Zwartruggens, a wild, difficult, and confusing district admirably adapted to Boer guerilla.
On September 29 Kekewich took up a position at Moedvil near the right bank of the Selous River. He was compelled to place all his westward outposts, except one double picket, on the right bank, as the veld on the left bank was bushy and rose gradually from the river and would have absorbed more men than he could spare for outpost duty.
Delarey was accurately informed of Kekewich's movements, and it is said had actually reconnoitred the camp unobserved a few hours after Kekewich's arrival. He quickly formulated his plan of attack, in which he seems to have followed, on a smaller scale, the familiar tactics of the British leaders whom he had met in battle, notably at Diamond Hill, but with a certain innovation of his own.
He divided his force into four columns, two of which were told off to grapple Kekewich's flanks and command his line of retreat, and two to make a frontal but not merely holding attack on his centre. Early in the morning of September 30 Delarey put his columns in motion. He started with certain points in his favour. All Kekewich's outposts save one were on the right bank and in the vicinity of the camp, and in fact Delarey took him by surprise. The movements of the Boer columns were, however, not well co-ordinated. The flanking columns were not in position when the centre columns, which do not seem to have been challenged by the post on the left bank, reached the river and concealed themselves in the deep bed. This might not have marred the success of Delarey's plan if the columns in the river-bed had not been discovered by a patrol which gave the alarm and brought them prematurely into action.
The situation now resolved itself into an attempt to storm the position. The centre columns sprang out of the river while it was still dark, mounted the steep bank and opened fire up the slope on to the camp on the skyline above. A stampede of the horses ensued, but a resolute front was quickly formed and the attack was checked. An alarm that the enemy was threatening the rear of the camp was proved to be unfounded by a scratch gathering of details which was hastily mustered; it then wheeled round, and picking up reinforcements on the way charged the Boer left at the river. The charge was irresistible, and the sun had hardly risen when Delarey's whole line fell away.
No limit can be assigned to the British soldier's power of resistance when he finds himself in a tight place, but it would probably have gone hard with him if Delarey's tactical scheme had been accurately carried out, and if the flanking columns, one of which was under the command of Kemp, had been further in advance when the centre columns were discovered. A panic among the horses which threw the camp into confusion, supervening on an unexpected attack while the dawn had scarcely shown above the Magaliesberg, was soon followed by a cry that the position had been turned. Yet at that critical moment of the dark hours, when animal courage is supposed to be at its lowest ebb, Kekewich's men never wavered, and although they were only called upon to deal with a blundered manoeuvre, yet it exacted from them a toll in casualties of nearly one fourth of their strength. Kekewich was wounded, and the loss of horses and transport pinned him to the ground until he was relieved by a column from the south, which had marched to the sound of the battle.
A few days later Kekewich went to Rustenburg, out of which he again sallied forth on October 13 into the Zwartruggens in search of Delarey. Methuen had already left Mafeking on the same errand. On October 24 Delarey fell in with one of Methuen's columns on its way to Zeerust. The column, which was impeded by wagons slowly progressing along a bad road in a defile, was pounced upon unexpectedly and hewn in twain; but if, as usual, the scouting was poor the defence was excellent. After a struggle which lasted two hours Delarey was driven off, the severed portions of the column were re-united, and not one of the seven guns was lost.
By the end of 1901 all the precedents of European warfare had been discredited. Tactics and strategy, as practised by the experts, had done their best, and were now in bankruptcy. The war had drifted into its final mechanical phase: the coercion of brute force by brute force of higher potential. It was now mainly a question of putting as many men as possible on horseback to ride down the enemy. Field guns not being needed, the Royal Artillery was formed into a corps of Mounted Rifles.