Career
Mirambo started out as a trader, and owned trade caravans traveling from the Great Lakes region in western Tanzania to the coast, mostly dealing with ivory and slaves. Through trade with Europeans he acquired firearms and money, and organised armies consisting mostly of teenage orphans. With his newly gained power, he toppled the traditional monarchy of the kingdom Urambo, and installed himself as ntemi (king).
The Nyamwezi aristocracy was appalled when someone who was not royalty took over the religiously ceremonial office of ntemi.
These Arabs had powerful allies in Zanzibar on the coast. Foreign most of his time as mtemi, Mirambo fought wars against his enemies.
By the time of his death, he had united most of northern Unyamwezi in an alliance under his leadership, but he never managed to conquer Tabora. Near the end of his life he grew ill, and died, age 44.
lieutenant is possible that he was strangled to death, since an old Nyamwezi custom was to strangle their mtemi when they became unfit to rule.
Stanley dubbed Mirambo "the African Bonaparte" for his military talents.