However, in their haste, the British had set off during the rainy season and this bogged down the columns, slowing their advance and gave the Zulus amble time to react. The British had hoped the Zulus would be dispersed harvesting their crops but the invasion happened to coincide with a routine muster of the army so that it was possible for the Zulus to react immediately to the oncoming threat. King Cetshwayo was alerted to the British presence and dispatched an army of about 24,000 warriors to intercept them. The Zulu warriors, led by Ntshigwayo kaMahole, greatly outpaced the British and undertook careful screening measures to ensure that they were not sighted by their enemy. In no time at all they were within striking distance of the British column under Lord Chelmsford which had pitched camp at Isandlwana on January 20. Greatly overconfident, the British failed to entrench or take any precautions for an attack. Lord Chelmsford was more concerned with the logistical problem of supplying his army in a vast wilderness than he was with defense.
In contrast, the Zulu princes were quick to recognize that they had caught their enemy at an extreme disadvantage and immediately seized the initiative and gave orders for an attack using classic Zulu tactics. On January 22, 1879 the Zulus came forward using about 10,000 to 15,000 men of their total strength of about 20,000. Colonel Pulleine deployed his few troops into a thin semi-circle to meet the on-rushing Zulus. Some British units, such as the rocket battery, were taken by surprise and overrun almost immediately. The Zulus fanned out in their classic “buffalo” formation and their center was held off for a time, taking considerable casualties due to the rapid, disciplined volley-fire of the British regulars with their modern rifles. However, the “left horn” of the Zulu “buffalo” made a determined and tenacious attack and soon had the British right flank crumbling away. Colonel Anthony Durnford and his men on the right flank had been the first to come under attack and finally his men were forced to retreat in the face of the Zulu onslaught. This allowed the African warriors to get around the fire of other nearby units and overwhelm them. Colonel Pulleine finally ordered his men to fall back to their camp, which the regulars at least accomplished in good order.
Lord Chelmsford and his force, alerted to the battle, returned late in the day but found nothing left and proceeded on to the mission station at Rorke’s Drift. The battle of Isandlwana was a stunning blow to the pride of the British Empire. The invasion of Zululand was totally defeated and had to be given up entirely. The Zulus had won a great victory and successfully defended their homeland. However, being so isolated, the victory gave them no long-term strategic advantage. It would be only a matter of time before the British attacked again, with more men, more caution and a greater determination to have their revenge. For a time though, after news of the epic Zulu victory spread, British positions throughout South Africa fell into near-panic at the fear that the Zulus might follow-up their success with a large-scale invasion south. However, King Cetshwayo was no fool and gave strict orders to his army against crossing the border. He wanted it made clear that they were fighting a defensive war only and would remain on their own territory. He hoped to avoid a full-scale war with Britain but, though the Disraeli government in London fell, that hope was in vain. The British high command feared that if the defeat at Isandlwana did not go unanswered it might encourage native wars and rebellions in other parts of the British Empire.