Robert C. Preller was born on 5 May 1846 at Pietermaritzburg and moved to the Transvaal in 1861.
When the war against the Basoetho started five years later he was in the Orange Free State and under veldcornet F. van Niekerk and Commandant Theunis Botha he was part of the battles at Nauwpoort, Thaba Bosego and Korranderberg.
He was assistant veldcornet during the wars against Sekoekoeni and those against Mapoch as a burger.In 1893 he was appointed as a member of the Zoutpansberg Occupation Commission and was in this position till 1895.
With the outbreak of the war he was appointed as Commandant over a commando existing of burgers of Johannesburg ans Pretoria, They was instructed to go and protect the southern border of the Free state.
Under generals H.R. Lemmer, de la Rey and the Chief Commandant of the Orange Free State he fought in the battle against the British army that freed Kimberley from the siege. He was also part of the battles of Rensburg siding and Colesberg.
On 7 September in the Rustenburg district he was wounded and sent to the Shajahanpur camp in India as a prisioner of war.