On December 7, by which time considerable reinforcements had come in, Gatacre felt himself strong enough to tackle Olivier at Stormberg. His plan was to take his column by train as far as Molteno, whence a night march of about eight miles would bring it into position for attacking the Boer laager. The use of the railway would not only enable him to strike more suddenly and with a greater chance of taking Olivier by surprise but would also economise the strength of his force, a portion of which having left the transports only a few days previously was not yet in hard condition. The force with which he proposed to take Stormberg amounted to 2,600 men, who detrained at Molteno soon after sunset on December 9. Gatacre calculated that after a march of about six hours he would be able to rush the position before dawn.
The Boers, to the number of 1,700 men, were in occupation of the Kissieberg ridge, and of a nek which runs westward from its southern end towards a higher hill overhanging Stormberg Junction called Rooi Kop. Gatacre had originally intended to attack the Boer position frontally, but the reports which he received on arrival at Molteno determined him to turn it. The change of plan was not made known to all the troops, with the result that the ambulance and ammunition wagons left the town by the Stormberg road instead of by the Steynsburg road, along which the rest of the column was marching to the new objective. No trustworthy maps were available, and the enterprise was dependent for its success upon the knowledge and fidelity of a sergeant of police and a few native constables who acted as guides and who professed to know "every inch of the way."
Soon after midnight, however, Gatacre's suspicions were aroused by the sudden appearance of a railway which ought not to have been there, and it was discovered that the guides had a mile or two back missed a path on which the column should have diverged to the right. They assured him, however, that they had chosen a better road and that he was now less than 3,000 yards from the Boer position. He therefore halted the column for an hour's rest, and hoped for the best.
When the march was resumed another railway was almost immediately encountered. It was in fact the colliery line which had been crossed before the halt and which here curves almost to the extent of a semicircle; but Gatacre believed that he had come upon the main line to Steynsburg and judged that he was now N.W. of the Boer position; while many of the officers in the rear of the column, unaware of the change of plan, imagined that they were approaching it from the S.E. along the Stormberg road originally selected for the advance on which the ambulance and ammunition wagons had already gone astray.
The direction of the march was now almost reversed, owing to Gatacre's misapprehension of his position; and at dawn the column unknown to itself reached certain cross roads on Van Zyl's farm which had been fixed upon as the point from which the attack should be delivered; but the locality was not recognized by the staff, and the guides, who seem to have misunderstood the object of the march, conducted the column still deeper into the valley beneath the Kissieberg ridge.
Suddenly a shot from the heights startled the errant and plodding column. The Boers had indeed been taken by surprise, but were at once on the alert and the crest line was soon occupied. The column marching in fours halted and turned to the right and, except the leading companies of Irish Rifles, which were formed to the front in order to seize a detached hill at the end of the ridge, sprang up the slope, but were soon baffled by the irregular tiers of krantzes or rock walls on the hill side. The artillery diverged to the left, losing one gun in the donga which ran down the valley, and took post on the detached hill from which the Kissieberg ridge could be shelled. The companies of Irish Rifles, after seizing this hill, passed along the nek which joined it to the ridge and almost won the crest line.
Meanwhile the Northumberland Fusiliers and the remaining companies of the Irish Rifles found the task of mounting the encumbered slope beyond their powers, and were soon ordered to fall back into the valley. The artillery noticed the movement, and in order to cover the retreat opened upon Kissieberg; not perceiving in the eastern dazzle of the sun about to rise above the sky line that some of the infantry who had not heard the order to retire were still clinging to the darkened westward hillside, and these were shelled by their own guns.
Gatacre, confident of an easy success, had thrown all his infantry into the firing line, and had no reserves to fall back upon to support the companies of the Irish Rifles which were still holding their own on the left flank of the attack. As soon as the troops had crossed the valley to reform on the opposite ridge a new entanglement beset them.
A commando under E.R. Grobler and Steenkamp, chiefly composed of rebels, which had been sent by Olivier on the previous day to stir up trouble in the district, was halted for the night a few miles out on the Steynsburg road. The sound of the firing quickly called it to attention, and a position which seriously threatened Gatacre's line of retreat was quickly seized. The commando, however, was handled with little judgment or energy, and was soon checked by the field guns which had been withdrawn from the detached hill near the Kissieberg ridge to cover the retreat of the infantry; and which at one time were firing trail to trail, some still engaging Olivier on Kissieberg while others were shelling Grobler.