sentences:  Since the Zulus controlled this territory, the Voortrekker leader Piet Retief paid a visit to King Dingaan, where the suspicious Zulu promptly killed him.This killing triggered other attacks by Zulus on the Boer population, and a revenge attack by the Boers.The culmination came on 16 December 1838, in the Battle of Blood River, fought at the Ncome River in Natal.