The 1st Battalion sailed on the Braemar Castle and Goorkha at the beginning of January 1900, and arrived at the Cape about the 26th. Along with the 2nd Norfolk, 2nd Lincoln, and 2nd Hampshire, they formed the 14th Brigade under Brigadier General Chermside, and part of the VIIth Division under Lieutenant General Tucker. For work of the brigade and of the division see notes under 2nd Norfolk Regiment.
In the fighting which took place between 18th February—the battle of Paardeberg—and the 27th, when Cronje surrendered, the KOSB were several times sharply engaged, particularly on the 23rd, and did most excellent work in repelling and defeating the Boer forces coming to Cronje's assistance.
Two officers, 2 non-commissioned officers, and 1 private were mentioned in Lord Roberts' despatch of 31st March 1900.
In the action at Karee Siding, fought on 29th March, to clear some hills held by the Boers north of Bloemfontein, the KOSB had very heavy work, losing 1 officer and 14 men killed, and 3 officers and 42 men wounded.
When Uitval Nek, garrisoned by the Lincolns, was attacked on 11th July, the KOSB were hurriedly despatched from Pretoria to their assistance, but they did not succeed in arriving before the post fell.
In July 1900 a fresh brigade was put together under Colonel G G Cunningham, DSO, of the Derbyshire Regiment, consisting of the KOSB, 2nd Berks, 1st Border Regiment, and 1st Argyll and Sutherland Highlanders; and this brigade, along with Hickman's Mounted Infantry, the Canadian and Elswick batteries, two 6-inch howitzers and 5-inch guns, was placed under Lieutenant General Ian Hamilton. His force was ordered on 16th July to go twenty-five miles north of Pretoria, then swinging to its right, it formed the extreme left of the army for the eastern advance, Mahon coming in between Hamilton and the centre. On 21st July Mahon and Hamilton combined at Doornkraal, Hickman returning to Pretoria with empty waggons. On 22nd July the force was seven miles north of Bronkhorst Spruit, and on the 25th Balmoral was occupied. Immediately after this Hamilton's force, with Mahon, was ordered back to Pretoria to operate against the enemy in the Rustenburg district. He left Pretoria on 1st August, and on the 2nd had some stiff fighting at Uitval's Nek, where the troops behaved splendidly, two companies of the Berkshires climbing a steep cliff overlooking the pass on the east. This caused the Boers to flee, abandoning waggons and horses. The KOSB got back to Pretoria about the end of August, after a march which all who took part in it will remember on account of the extreme modesty of the rations. So scanty was the supply that before Pretoria was reached the health and fitness of the brigade was becoming affected. After two days' rest and hurriedly refitting the column set off towards another destination, Belfast on the Delagoa line.
The battalion, like many other regiments, was told off to garrison some stations and posts on that railway when the brigade arrived at Balmoral on 4th September.
Twelve officers and 20 non-commissioned officers and men were mentioned in Lord Roberts' final despatch.
In 1901 the battalion was brought into Pretoria, and early in May was taken to Krugersdorp. At Nauwpoort Nek they joined a column under Brigadier General Dixon, himself an old Borderer. The column operated in the dangerous Megaliesberg district. At Vlakfontein on 29th May 1901 Dixon's force was fiercely attacked; four companies of the KOSB were present, but the fighting chiefly fell to some of the Derby Regiment, who were with the left and rear, the points attacked (see Derbyshire Regiment). Colonel Kekewich, who had been in command at Kimberley, took over the column, which continued to hunt the kloofs, dongas, and spruits of the Megaliesberg with wonderful success. In his despatch of 8th September 1901 Lord Kitchener, referring to a capture on 10th August of 40 Boers, including Mr Wolmarans, chairman of the late Volksraad, says, "The majority of these prisoners, who were fully equipped with rifles, horses, and saddlery, were taken by the Volunteer Service company of the KOSB under Major Mayne". Major Mayne and several men were commended in despatches for this affair.
In September 1901 the battalion relieved the West Yorkshire Regiment on the Mooi River blockhouse line.
In January 1902 Major Mayne superintended the construction of a new line. Several attacks were made on the line in April and May. On the 13th May President Shalk-Burgher, Generals Delarey, Kemp, and Celhers, and other prominent Boers, came into the blockhouse line and were escorted to Krugersdorp on the way to the peace discussion.
The Mounted Infantry company of the regiment did much hard work and had some stiff fighting, particularly at Lambrechtfontein, Orange River Colony, 18th May 1901, when they had eight casualties.
Several members of the company gained mention during the campaign for very excellent work. In the
final despatch 3 officers and 3 non-commissioned officers of the battalion were mentioned.
