After the fall of Port Natal Port Natal Andries Pretorius arrived from Graaff-Reinet. On 25 November 1838 Pretorius took over leadership as Commandant-General of the Voortrekkers in Natal. He immediately re-organised the Voortrekkers and started to prepare a retaliatory attack on the Zulu.

On Sunday, 9th December, Pretorius and his followers made a vow to God that in the case of victory; they would build a church to honour God and they would tell there children to observe a day of thanksgiving. (Recent research has put a question mark over the vow and its existence as 'thanksgiving' was not commemorated in the years immediately following the battle, but the church was built).

The Pretorius party crossed the Ncome (Buffalo) River, and on Saturday 15 December, they reached a tributary (Thukela). Their scouts reported that a large AmaZulu force was advancing (10 000-20 000 Zulu warriors). The Zulu army was led by Dingane's generals Dambuza (Nzobo) and Ndlela kaSompisi. After the scouts had given the warning the Voortrekkers moved there wagons into a laager (circular formation) in the best strategical position possible, between a deep pool in the river and a donga (a large ditch). The Voortrekkers force consisted of 470 men. There were only two gaps in the laager and in each, a canon was placed.

16 December 1838: The Battle

At dusk on the 15th December the Amazulu had already begun to circle the laager. A heavy mist surrounded the laager and only lifted in the early hours of the morning, this made visibility poor. At dawn on the 16th December 1838 the Zulu warriors equiped with assagais and shields swept towards the laager. To be able to use their assagais effectively they had to come as close as possible to the defenders.

The Voortrekkers were equiped with far superior weaponry and responded to the Zulu advancement with musket and cannon fire.  Eyewitnesses and writers differ slightly on the exact details of the battle, but at dawn when the first Zulu attack began, the firing was apparently so heavy that the Zulu warriors could not be seen through the smoke. The main shortcoming of the Voortrekkers weapons was the lengthy reloading times. The first Zulu attack had scarcely been repulsed when a second was launched, this time the Zulu warriors almost reached the laager... Meanwhile hundreds of warriors were hiding in the donga. Sarel Cilliers and 80 others attacked them during a short lull in the fighting. When the Zulu's, who had withdrawn about 50 yards from the laager, failed to launch a third attack, Pretorius sent some men to draw them out to seal the victory. Pretorius' cavalry met with determined resistance from the Zulu Warriors, and it was only after a third sortie that the Zulu's were put to flight, pursued by the Voortrekkers. At midday the pursuit was called off. More than 3000 corpses were counted around the laager. Only, 3 Voortrekkers (including Pretorius himself) were wounded, none were killed. The Ncome River became red with the blood of the slain. Hence the battle became known as the battle of "Blood River".

After this defeat, the Zulu kingdom never really recovered. Dingane's half-brother Mpande allied with Pretorius to defeat Dingane, who was eventually killed by the Swazi as he tried to regroup further north. Europeans now increasingly began to dictate the nature of Zulu politics.

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