Ten years of warfare placed incredible strains on the Zulu nation. Shaka, unstable and worried about being replaced by an heir, finally snapped into madness after the death of his mother in 1828. He imposed a year of celibacy on his people. He killed anyone who did not show enough sadness at the death of his mother. He was killed within the year by his half-brother, Dingane, who succeeded him as ruler. 