Cetshwayo's success as a leader led to a conflict with Mpande's second, and favourite, son Mbuyazi. Though Cetshwayo was the oldest, he was not officially successor, as his mother had not been declared the king's Great Wife. Either brother could inherit if Mpande chose their mother as his Great Wife, which he did not. Cetshwayo felt that his father was favouring Mbuyazi, and both sides developed factions of followers. Mpande ceded territory to Mbuyazi on the Tugela River, where he and his followers settled. Mbuyazi also cultivated support from European settlers led by John Dunn. Cetshwayo, who was supported by most of the territorial sub-chiefs, decided to settle the matter militarily. He invaded Mbuyazi's lands and crushed his followers at the Battle of Ndondakusuka, massacring survivors, including five of his brothers. Dunn escaped and later became an adviser to Cetshwayo.