The first contingent, an infantry company, arrived in South Africa in late November 1899, and served with the Australian Regiment guarding a railway line.

The second contingent, a mounted squadron, had arrived in South Africa in late February 1900, participating in the suppression of a Boer uprising before joining the march to Bloemfontein.

[2] With the regiment, it marched to Enslin on 10 December to relieve the Gordon Highlanders under the orders of Lieutenant-General Lord Methuen, after which it was held in reserve at the Battle of Magersfontein, in which it did not participate.

With the regiment, the 1st SAMR became part of the British force commanded by Major-General Ralph Arthur Penrhyn Clements, holding positions in front of Colesberg.

Following the engagement the British retreated towards Rensburg and to Arundel on the night of 13–14 February, where the regiment suffered multiple casualties while serving as the rearguard of the column.

The squadron participated in the subsequent march to Bloemfontein as part of the column of the Inniskilling Dragoons under Major Dauncey, on the right of Clements' force.

It marched to Britstown and joined the column of Colonel John Adye after arriving at De Aar, participating in the relief of Prieska during a Boer uprising in that area.

[8] After returning to De Aar, it moved to Norval's Pont by train, then marched to Bloemfontein under Major Euthoven of J Battery Royal Horse Artillery.

It served as the advance guard of Pole-Carew's 11th Division in the march to Johannesburg,[10][11] capturing seven engines while cutting the Pretoria railway under fire at Elandsfontein on 29 May.

Lieutenants George Lynch and Rowell were handed the keys to the fort, over which the Union Jack was raised; 85 Boers surrendered to them that day.

[10][11] After Belfast, the SAMR marched along the Pretoria–Delagoa Bay Line to Komatipoort on the border with Portuguese East Africa via Helvetia, Machadodorp, Nooitgedacht, Kaapsehoop, Barberton, and Hectorspruit.

The remainder of the second contingent was attached to Brigadier-General Edwin Alderson's Mounted Infantry Brigade, serving in east and northeast Transvaal until March 1901.