The Voortrekkers, now worn out through the death of their second leader Gert Maritz, and through internal quarrels, were at the end of their power. Only their newly elected leader Andries Pretorius was successful in consolidating the group and preparing it for a retaliatory strike against the Zulu king. On December 16, 1838 the Zulus were completely defeated in the famous "Battle of Blood River". This enabled the founding of the first short-lived Boer Republic in Natal, with Pietermaritzburg as its capital. By 1842, British troops occupied Port Natal, today's Durban, and annexed the hinterland as a Crown Colony. The Voortrekkers retreated behind the Drakensberg.
The Great Trek was organized in resistance to the politics of the Cape government. In 1835, the first groups set out. Under the leadership of Louis Trichardt and Hans van Rensburg, they opened up the north of today's Mpumalanga. Other groups, under the command of Andries Pretorius, Gert Maritz and Piet Retief followed. In the area around ThabaNchu in what would become the Orange Free State, a huge Boer camp of 5,000 Voortrekkers eventually gathered.
They headed for Natal to gain land for settling and grazing. To that end they had to negotiate with Dingane, the king of the Zulus. The negotiations ended with the agreement that large areas in central and south Natal would be ceased to the Boers. However, when the delegates under Piet Retief prepared to leave, they were lured by the Zulus into an ambush and killed. Then the Zulu warriors fell upon the Voortrekkers who had made camp at the foot of the Drakensberg to wait for the return of their leaders. The Zulus killed 500 of them and stole almost all their cattle. Read thereport of an eyewitness.