Following the despatch of the first contingent from New South Wales to the Boer War, a second contingent was quickly sent. One squadron from the Mounted Rifles Regiment had an infantry company which later became mounted. It was then decided to raise other squadrons, "B", "C", and "D", of the 1st Regiment, which would join "A" and "E" Squadrons already in action. In recruiting the new force, "good shots and good riders" were required and preference was given to those serving or had served in the colonial forces. Members of the reserve and civilian rifle clubs were also eligible.

The regiment's three squadrons embarked at Sydney on the transport Southern Cross on 17 January 1900 and disembarked at Cape Town, South Africa, a month later. The three squadrons consisted of 20 officers and 385 other ranks, and 404 horses. There were eight veterans from the Sudan among the regiment.

The regiment served in South Africa for just over a year, during which time it served in the Orange Free State, the Transvaal, and in western parts of the Cape Colony. Upon arriving, the regiment became part of Le Gallais's brigade, which was part of Lord Robert's main column. In March the regiment participated in the advance from Modder River to Bloemfontein and Le Gallais's brigade took up a position near Brandfort. The regiment absorbed A Squadron in the same month, the 1st West Australian Mounted Infantry the next month, and then E Squadron in May.

Thus strengthened, the regiment severed with General Hutton's force, participating in the general advance to Pretoria, moving from Bloemfontein to Kroonstadt. It then became part of De Lisle's Column, Ridley's Brigade, which was part of General Ian Hamilton's force, advancing from Kronnstadt to Pretoria.

The principle engagements in which the unit was engaged were:

Poplar Grove: 7 March 1900
Dreifontein: 10 March 1900
Bloemfontein: 14 March 1900
Karee Siding: 29 March 1900
Thaba 'Nchu: April 1900 (a detachment only)
Brandfort: 3 May 1900
Vet River: 5 May 1900
Zand River: 10 May 1900
Kroonstad: 12 May 1900
Lindley: 20 May 1900
Near Johannesburg: 29 May 1900
Pretoria: 4 June 1900
Diamond Hill: 11-12 June 1900
Heidelberg: 23June 1900
Wittebergen: July 1900
Palmietfontein: 19 July 1900
Vredefort: 24 July 1900
Venterskroom: 7 August 1900
Alexanderfontein: 14 August 1900
Boschfontein: 10 September 1900
Schoeman's Drift: 27 October 1900 (captured a Boer Krupp gun)
Bothaville: 5-6 November 1900
Honwater: 26 December 1900
Machadodrop: October and November 1900

The regiment spent its last months in South Africa, operating in the Cape Colony from 20 December 1900 to March 1901. At the end of March the regiment embarked at Cape Town and returned to Australia, travelling via Fremantle and arriving at Sydney on 19 April. The troops disembarked on 1 May.
References
  • Official records of the Australian military contingents to the war in South Africa(Melbourne : A.J. Mullett, Govt. Printer, 1911)
  • Wilcox, Craig, Australia's Boer War : the war in South Africa, 1899-1902(Melbourne : Oxford University Press, 2002)
    • CategoryUnit
      Related conflicts South Africa, 1899-1902 (Boer War)
      Battle honours South Africa 1899-1902
      Commanding officers Knight, Guy Cunninghame
      Alternative names
      • 1 New South Wales Mounted Rifles
      • 1 Regiment New South Wales Mounted Rifles
      • 1st New South Wales Mounted Rifles
      • First Australian Regiment New South Wales
      • First Australian Regiment New South Wales; First New South Wales Mounted Rifles, E Squadron
      • First Australian Regiment, New South Wales
      • First NSW Mounted Rifles, Regiment HQ
      • First New South Wales Mounted Rifles, B Squadron
      • First New South Wales Mounted Rifles, C Squadron
      • First New South Wales Mounted Rifles, D Squadron
      • First New South Wales Mounted Rifles, E Squadron
      • First New South Wales Mounted Rifles, E Squadron; First Australian Regiment
      • First New South Wales Mounted Rifles, E Squadron; First Australian Regiment New South Wales
      Unit hierarchy