It is stated that on the previous evening there was no intention on the part of the Zulus to attack the camp upon the 22nd, which
was not thought by them a propitious day, being that of the new moon. It is also said that the Zulu army came with pacific intentions, in order to give up Sihayo's sons, and the cattle for the fine. In all probability they left the king with such orders that is to say, to make terms if possible, but to fight if forced to it, and if the English intentions were plainly hostile. This hostility was thoroughly proved before the morning of the 22nd, when the departure of Lord Chelmsford's force from the camp must have been a strong temptation to the Zulus to attack the latter.
Source "History of the Zulu war and its origin;"