Unconcerned by the presence of the Zulus nearby, Chard returned to his tent by the river crossing, but he was soon after disturbed by two NNC officers on horseback who informed him that the camp at Isandlwana had been overwhelmed and annihilated by the Zulus. Returning to the station, Chard found Bromhead and Assistant Commissary James Dalton had already instructed the troops to use mealie bags to construct a defensive perimeter between the storehouse and hospital. Chard consented and by 4 pm the hastily constructed perimeter was complete. Soon afterwards, the Zulu "impi", which contained some 3,000–4,000 men, was sighted advancing on their position. This caused the NNC troops to panic and desert the station, reducing the number of defenders from around 350 to approximately 140 (including 30 sick and wounded). Chard immediately ordered an additional barricade of biscuit boxes to be built across the inner perimeter to provide a smaller fall-back area should the Zulus overwhelm a part of the thinly manned perimeter.