The regiment was one of those which were so opportunely despatched from India to South Africa in September 1899. They landed at Cape Town, and when war broke out had to do an immense amount of patrol work, as mounted men were so scarce in the colony. When Lord Methuen commenced his advance from Orange River in November (see 3rd Grenadier Guards), the 9th Lancers, three companies Mounted Infantry, and some of Rimington's Guides were his only mounted forces,—an utterly inadequate complement for practically three brigades of infantry.
At Belmont, 23rd November 1899 (see 3rd Grenadier Guards), the regiment had very responsible work—two squadrons with one of Mounted Infantry protecting the left flank; one squadron and some of Rimington's Guides and a company of Mounted Infantry worked to the east. At Enslin on the 25th they had plenty— too much—to do. In closing his despatch as to Enslin Lord Methuen says, "My guns played on the masses of horsemen, but my few cavalry, dead beat, were powerless, and for the second time I longed for a cavalry brigade and a horse-artillery battery to let me reap the fruits of a hard-fought action". The want of cavalry caused Belmont, Enslin, and Modder River to be purely infantry actions, and wellnigh barren ones. Some critics, such as Mr Maydon, have expressed the opinion that Lord Methuen should have delayed his advance till more mounted troops were available, but the perils of the Diamond City bulked largely in the thoughts of all at the time. At Modder River, 28th November, the 9th Lancers and Mounted Infantry protected the right flank, where the Boers were threatening all day. Mr Maydon, p 45, records that the regiment reported on the previous day the enemy intrenched in the river-bed, but that Lord Methuen refused to believe it. This statement is not altogether unsupported.
At Magersfontein, 11th December, the regiment did much dismounted work on the right flank, and their services were very valuable. "Major Little in the firing line did good work all day"; and Lieutenant Allhusen's work with the maxim was also mentioned in the despatch of 15th February 1900. About 9th January 1900 the regiment took part in a raid into the Orange Free State. When the march to Kimberley commenced on 11th February the 9th and 16th formed the 3rd Cavalry Brigade under Brigadier General J R P Gordon. In the rush through the Boer position on the morning of the 15th February the 9th and 16th had a prominent place, heading the charge, and they did very well (see Maydon's book and Cecil Boyle's article in 'Nineteenth Century' of June 1900). After Kimberley was relieved the brigade took part in the other operations antecedent to the occupation of Bloemfontein, but were not in the force which headed off Cronje on the 17th. The 3rd Cavalry Brigade remained at Kimberley till the morning of the 18th, and arriving at a point north of the Boer force late in the afternoon, Gordon had a little fighting on his own account, his batteries O and R doing some good work. Next day he joined French, and acted with him in all the other fighting on the way to Bloemfontein.
In Lord Roberts' despatch of 31st March 1900, 3 officers and 5 non-commissioned officers and men of the 9th Lancers were mentioned for exceptional work up to the occupation of Bloemfontein.
On 29th March 1900 the 1st and 3rd Cavalry Brigades under French were, with Tucker's VIIth Division, employed at Karee Siding when the enemy was driven back towards Brandfort.
Towards the end of April the brigade was engaged with Ian Hamilton and French in clearing the enemy from the Thabanchu district, and had some stiff fighting on the extreme right (see Duke of Cornwall's Light Infantry). Lord Roberts commenced his northern advance on 3rd May, and on the 8th he was joined by General French with the 1st (Porter's), 3rd (Gordon's), and 4th (Dickson's) Brigades of cavalry. The 3rd Brigade now included the 17th Lancers. In the further advance towards Pretoria this brigade was generally working in advance on the right flank of the main body and under the direct orders of Lord Roberts, General French with the 1st and 4th Cavalry Brigades and Button's Mounted Infantry being far out on the left flank.
At Diamond Hill (see Sussex Regiment) the 2nd and 3rd Cavalry Brigades were on the right, the 3rd Brigade being on the extreme right but thrown back. Both brigades were opposed by strongly posted forces of the enemy, and were at times pressed to hold their own. Their losses were considerable. The 3rd Cavalry Brigade thereafter took part in the initial steps of the movement which led up to Prinsloo's surrender. On 11th July the brigade left Sir A Hunter's force, returning via Reitz to Heilbron and thence to Kroonstad. Brigadier General Gordon at this time left the 3rd for the 1st Brigade, his successor being Lieutenant Colonel Little. The 2nd and 3rd Brigades were for some weeks after 16th July engaged in the pursuit of De Wet's force, which had broken out of the Brand water basin (see 1st Northumberland Fusiliers). About the middle of August the 3rd Brigade moved with Lord Methuen to Zeerust. As the brigade was starting to return on the 25th, Colonel Little was wounded and Colonel Dalgetty of the Colonial Division took command. Between Zeerust and Krugersdorp there was constant fighting. Brigadier General Porter now got the brigade, and under him it was railed from Johannesburg to Kroonstad to operate once more against De Wet. The brigade was for a time employed in the Orange River Colony, sweeping up, and on the borders of Cape Colony. In November 1900 the brigade was split up, but was mainly employed in the various columns put into the field to prevent, if possible, De Wet and other leaders from entering Cape Colony. The 9th Lancers acted for a time with General Charles Knox.
Ten officers and 12 non-commissioned officers and men of the 9th Lancers were mentioned in Lord Roberts' despatches of 2nd April and 4th September 1901.
Early in the year 1901 the regiment was sent into Cape Colony to pursue Boers who had crossed the Orange, and, acting under Colonel Scobell, they and the Cape Mounted Rifles gained great credit for their successful endeavours to close with the enemy. Over and over again this column surprised laagers and killed or captured many of the enemy. In particular, they were specially praised for the capture of Letter's commando on 5th September 1901. Lord Kitchener described it as a brilliant success. In this affair the 9th lost 7 killed and 5 wounded. During the remainder of the campaign the regiments of the brigade were mainly employed in Cape Colony. The 9th sailed for India in March 1902, after two and a half years' campaigning. Their war services were as continuously hard, as brilliant, and as fruitful as those of any other regiment in South Africa.
For exceptional work in the later phases of the war Lord Kitchener mentioned, in despatches written during the war, 6 officers and 10 non-commissioned officers and men of the 9th Lancers, and in the final despatch 4 officers and 4 non-commissioned officers and men were mentioned.