The majority of Voortrekkers, however, neither settle between the Orange and the Vaal nor trek to the north, but move northeastward around Lesotho and travel down toward the sea into Zulu-ruled areas of southeastern Africa.

The leader of this group, Piet Retief, attempts to negotiate with Dingane for permission to settle in relatively sparsely populated areas south of the Tugela River.

Dingane is at first receptive to Retief's entreaties, but then, apparently fearing that the introduction of European settlers will undermine his authority, he has Retief and seventy of his followers killed while they are at his capital in February 1838.

Dingane now sends out Zulu regiments to eliminate all Voortrekkers in the area; they kill several hundred men, women, and children and capture more than thrity-fibve thousand head of cattle and sheep.

Not all of the settlers are killed, however, and in December the survivors, reinforced by men from the Cape Colony, march five hundred strong to avenge the deaths of Retief and his followers. Commanded by Andries Pretorius, the Voortrekkers pledge that they will commemorate a victory as a sign of divine protection.

They then meet and defeated Dingane's army at the Battle of Blood River.

Their victory will be celebrated each year on December 16, the Day of the Vow.