Their role was to man coastal defences and fortifications, relieving the Royal Artillery (RA) for active service.

The first commandant was Lieutenant-Colonel William Geddes, CB, (1794–1879) a retired officer of the East India Company's Bengal Horse Artillery, who was given the honorary rank of colonel.

[5][6][7][8] Octavius Pelly, a Half-pay Captain in the Madras Light Cavalry was appointed Major-Commandant on 28 October 1865 and promoted to Lt-Col on 26 March 1872.

[1][5][7][9][10][11] Lieutenant-Colonel Alan Colquhoun, a former officer in the Black Watch and the 16th Lancers, was appointed commandant on 20 August 1887.

Thornhill commanded a composite company of Mounted infantry, which for two months provided the guards for all bridges and blockhouses from Colenso to Sandy's River on the Natal railway.

On 9 September 1901 the brigade moved to Kakkerstroom to collect a thousand Boer prisoners of war and escort them to Durban and thence by sea to Bombay, where the company remained to guard them until sailing for home in November 1901.

There were moves to reform the Auxiliary Forces (Militia, Yeomanry and Volunteers) to take their place in the six Army Corps proposed by St John Brodrick as Secretary of State for War.

[17][18] Under the sweeping Haldane Reforms of 1908, the Militia was replaced by the Special Reserve, a semi-professional force whose role was to provide reinforcement drafts for Regular units serving overseas in wartime.