The reign of Shaka marks a crucial phase in the history of the Zulu Kingdom. After Shaka had seized power, he further developed the disciplined organization of the military. He introduced the assegai (a short thrusting spear) and trained the army to encircle the enemy in a shield-to-shield formation so that rival warriors could be stabbed at the heart. These military-technical innovations were to be of enormous political importance. The efficiency of the military apparatus allowed Shaka to gather a large number of chiefdoms into one entity and to incorporate the defeated troops into the Zulu military. Though some chiefdoms were able to disperse into other territories, Shaka's wars resulted in the merging of some 300 formerly independent chiefdoms into the Zulu Kingdom.

In 1878, Bartle Frere, the British High Commissioner of South Africa, presented an ultimatum for Cetshwayo to disband the Zulu army, stop the many executions, as Shepstone had already advised during Cetshwayo's coronation, give missionaries the freedom to teach, and grant young Zulu men the freedom to marry. When the Zulu king did not conform to these demands, a succession of bloody confrontations between the Zulu and the British ultimately led to the Anglo-Zulu war of 1879, aiter which the Zulu Kingdom was brought under British colonial rule.