Umtonga kaMpande

Cetshwayo was a son of Zulu king Mpande[1] and Queen Ngqumbazi, half-nephew of Zulu king Shaka and grandson of Senzangakhona. In 1856 he defeated and killed in battle his younger brother Mbuyazi, Mpande's favourite, at the Battle of Ndondakusuka. Almost all Mbuyazi's followers were massacred in the aftermath of the battle, including five of Cetshwayo's own brothers.[2] Following this he became the ruler of the Zulu people in everything but name. He did not ascend to the throne, however, as his father was still alive. Stories from that time regarding his huge size vary, saying he stood at least between 6 ft 6 in (198 cm) and 6 ft 8 in (203 cm) in height and weighed close to 25 stone (350 lb; 160 kg).

His other brother, Umthonga, was still a potential rival. Cetshwayo also kept an eye on his father's new wives and children for potential rivals, ordering the death of his favourite wife Nomantshali and her children in 1861. Though two sons escaped, the youngest was murdered in front of the king.[3] After these events Umtonga fled to the Boers' side of the border and Cetshwayo had to make deals with the Boers to get him back. In 1865, Umthonga did the same thing, apparently making Cetshwayo believe that Umtonga would organize help from the Boers against him, the same way his father had overthrown his predecessor, Dingane.https://en.wikipedia.org/wiki/Cetshwayo