Lieutenant-Colonel Alexander Whitelaw Thorneycroft was born on 19 January 1859 in Wolverhampton in the UK.

He saw action in the Anglo-Zulu War and in the First Boer War of 1881 where he was involved in the Defence of Pretoria.

When the British anticipated the outbreak of hostilities in 1899, he was sent to South Africa to raise a local volunteer unit.

When the South African Was (1899-1902) broke out he had raised a corps of troop known as the Thorneycroft′s Mounted Infantry. His unit saw action in the battles fought in the Relief of Ladysmith, with the Battle of Spioen Kop being the action where he took charge of the forces on the summit, when the commander of the forces had been mortally wounded. He saw action in many of the battles in the guerrilla phase of the war.