Anglo-Zulu War regret. The ensuing Battle of Isandlwana was the greatest victory that the Zulu kingdom would enjoy during the war. The British centre column was wrecked and its camp annihilated with heavy casualties as well as the loss of all its supplies, ammunition and transport. The defeat left Chelmsford no choice but to hastily retreat out of Zululand. In the battle's aftermath, a party of some 4,000 Zulu reserves mounted an unauthorised raid on the nearby British army border post of Rorke's Drift and were driven off after 10 hours of ferocious fighting. While the British central column under Chelmsford's command
Anglo-Zulu War they left or protected if they remained. In addition, Frere planned to use the meeting on the boundary commission report with the Zulu representatives to also present a surprise ultimatum he had devised that would allow British forces under Lord Chelmsford, which he had previously been instructed to use only in defense against a Zulu invasion of Natal, to instead invade Zululand. Three incidents occurred in late July, August and September which Frere seized upon as his "casus belli" and were the basis for the ultimatum to which Frere knew Cetshwayo could not comply, giving Frere a pretext to attack