The 1st Battalion sailed on the Doune Castle about 24th November 1899, and arrived at the Cape about 15th December.
The 1st Yorkshire went out as part of Sir Charles Warren's Vth Division, but while Sir Charles with six of his battalions went on to Natal, the 2nd Warwicks and 1st Yorkshire were dropped at Cape Town, and this battalion went up to the Colesberg district to help General French in his efforts to repel the Boer invasion of the colony. The force under General French was largely a cavalry one, but he had fortunately some fine infantry, including four companies of the 2nd Berkshire, who had been in South Africa when the war broke out, the 1st Welsh, who arrived about 22nd November, and the 1st Essex, who arrived early in December; later he got the Suffolks, and then the Wiltshires and other regiments of the Vlth Division. While the din of Magersfontein, Colenso, and Spion Kop was in our ears we had little thought of the splendid work French was doing with a very slender force, but the events of the intervening years have taught us the inestimable value of that work. Had the enemy passed Naauwpoort, De Aar with its millions' worth of stores would have been at his mercy, Lord Methuen's communications would have been cut, and an advance by the Kimberley line made almost impossible.
The 1st Yorkshire had done their work in the Colesberg district without mistake, and when Lord Roberts in the beginning of February 1900 was making up a force for his great effort, the battalion, along with the 1st Essex and 1st Welsh, was taken to Modder River and there put into the 18th Brigade under Brigadier General T Stephenson, who at the time of his appointment was colonel of the 1st Essex. The other battalion was the 2nd Warwicks, which was then employed in the Britstown neighbourhood, and unfortunately did not join the brigade in time to take part in the triumph of Paardeberg. Evidently Lord Roberts desired to have in his force as many seasoned battalions as possible, as the 18th Brigade took the place of the 12th in the Vlth Division under Lieutenant General Kelly - Kenny, the 12th being left under General Clements in the Colesberg district, where most of the troops of the 18th had just been.
The work of the Vlth Division while acting together in the eastern advance has been sketched under the East Kent Regiment. Of that work the 1st Yorkshire took their share, as is proved by their losses. At Paardeberg on 18th February they had 1 officer and 30 men killed, 4 officers, including Colonel Bowles and Major Kirkpatrick, and over 100 men wounded. The heaviest regimental loss in that battle was that of the Seaforths, 33 killed, the Canadians and Welsh having about 20 each.
On the 20th the 1st Yorkshire again distinguished themselves in actions against parties of Boers who came to Cronje's assistance, they and the Buffs taking 80 prisoners. On the 23rd they were in a stiff fight and did very well. On 10th March at Driefontein the 18th Brigade were in the front, and had again very hard fighting. The East Kent, Welsh, and Essex were first line, the 1st Yorkshire and 2nd Gloucesters supporting. Late in the afternoon the bayonet had to be used to clear the position. This battalion on the 10th lost 3 killed and 23 wounded. Three officers and 2 non-commissioned officers were mentioned in Lord Roberts' despatch of 31st March 1900.
After the entry into Bloemfontein the Vlth Division, as previously constituted, was broken up; but the 18th Brigade had again good luck and a post of highest honour, being along with the Guards Brigade put into the newly-formed Xlth Division under Lieutenant General Pole-Carew. Under that general the 18th Brigade took part in the operations designed for the relief of Wepener and the driving from the south-east of the Orange River Colony of the strong Boer force which, during March and April 1900, was troubling the Commander-in-Chief by threatening his lines of communication and snapping up or defeating outlying columns, such as Broadwood's at Sannah's Post and the Royal Irish Rifles at Reddersburg.
In the northern advance, commencing 3rd May, the VIIth and Xlth Divisions composed the centre of the army; but they had no severe fighting such as they had previously seen, or indeed such as fell to the lot of the troops on the flanks.
The 18th Brigade entered Johannesburg on 31st May along with Lord Roberts, and they provided his guard of honour. On 5th June they marched into Pretoria.
At Diamond Hill, 11th and 12th June, Pole-Carew's Xlth Division, which still included the 18th Brigade, was in the British centre, following the railway line; but at that part the enemy's position was almost unassailable, and the whole of the two days' fighting was done near the flanks. On the 12th the Guards Brigade was moved to the right to support Bruce Hamilton, the 18th Brigade remaining in the centre.
The 18th Brigade, as part of the Xlth Division, took part in the eastern movement towards Koomati Poort (see 3rd Grenadier Guards), but in that movement the brigade had comparatively few casualties, as the most severe fighting was again invariably on the flanks. In Lord Roberts' final despatch 9 officers and 17 non-commissioned officers and men of the 1st Yorkshire were mentioned. In the desultory fighting which was to continue for another year and nine months the 18th Brigade were chiefly utilised for garrison work in the Eastern Transvaal, and none of the regiments had any serious losses in action.
In the first half of 1901 the battalion was on garrison duty about Koomati Poort, Kaapmuiden, Avoca, and Barberton, and suffered from fever so badly at the first-named place that over 50 per cent of the battalion was in hospital. At the end of July a half-company made a very fine march of forty-seven miles in thirty-six hours with a temperature of 110° in the shade, the object being to reinforce Steinaecker's Horse in Swaziland. In August the battalion was moved to Pretoria, and in September to Ladysmith in connection with the threatened reinvasion of Natal. In October they were entrained for Elandsfontein, near which they remained holding the line Springs to Viljeon's Drift to the close.
Although their opportunities were few, the Yorkshire Regiment were able to pick up a few mentions in the despatches of Lord Kitchener, written during the war, for exceptional work, chiefly with Mounted Infantry, and in the final despatch 2 officers and 4 non-commissioned officers and men were mentioned.