T.F.J. Dreyer was a member of the Potchefstroom commando and was part of the siege of Mafeking and the battles of the Western border and later escaped from the laager of General Piet Cronje at Magersfontein.
He was also at the battle of Abrahamskraal and after the occupation of Pretoria he was first appointed as veldcornet and later as Commandant.
He took part in the battles near Rustenburg, Klerksdorp and Potchefstroom and during the second part of 1901 with his 17 year old son he joined General J.C. Smuts with seventy men from Potchefstroom in the Orange Free State.
He did not succeed to reach the Cape colony and on 28 September 1901 after a short skirmish in the Southern Free State was taken as a prisoner of war and sent to India