The Battle of Spion Kop was fought about 38 km (24 mi) west-south-west of Ladysmith on the hilltop of Spioenkop along the Tugela River, Natal in South Africa from 23–24 January 1900.
The British suffered 243 fatalities during the battle; many were buried in the trenches where they fell. Approximately 1,250 British were either wounded or captured. Mohandas Gandhi was a stretcher-bearer at the battle, in the Indian Ambulance Corps he had organised, and was decorated. The Boers suffered 335 casualties of which 68 were dead.
Although the common English name for the battle is "Spion Kop" throughout the Commonwealth and its historical literature, the official South African English and Afrikaans name for the battle is "Spioenkop". Another variant that is sometimes found is the combination into "Spionkop".
The reason why the older spelling is used internationally is because the name "Spionkop" originates from Dutch; spion [spee-yawn], and not spioen [spee-yoon], is the Dutch word for "spy". Until the 1920s, Dutch was still the official written language of the Boers, which is why the older Dutch spelling persists outside South Africa. Within South Africa, the spelling was updated along with Afrikaans spelling reform and recognition of Afrikaans as a language in its own right.
Sources: https://en.wikipedia.org/wiki/Battle_of_Spion_Kop and http://samilitaryhistory.org/vol011nl.html