After the Voortrekker leader Piet Retief and a group of approximately 70 of his following, including two children were murdered during the celebration of a contract (to buy land for settlement)at the kraal of king Dingaan of the Zulus ; and the subsequent murders of approximately 500 settlers who were waiting for the confirmation of the contract nearby, the Voortrekkers assembled at the Ncome River for a decisive battle. On December 16, 1838, 464 Boers under the command of Andries Pretorius defeated more than 10,000 Zulu warriors, killing more than 3000 of them. The deeply religious Boers interpreted it as a divine answer to a vow that they have made earlier, on December 9th; during which they had prayed and made a vow that if God would grant them victory over the Zulus, they would build a church and commemmorate the event annually. The boers were armed with muzzle loaders and had two small cannons. The Zulus were armed with muzzle loaders that was obtained during the previous raids on the settlers, but most of them had throwing spears and stabbing spears (assegais).