At while Wood was riding along the southern flank of Hlobane he spotted five large columns of Zulu to the south-east. This was the main Impi, which he had not expected to arrive for another day and was closing on the British fast, only away. The Impi was already dispersing and Wood could see that they would block Buller's retreat from the upper plateau and then trap Russell. Even if Wood withdrew both groups, they would have to make a rapid retreat to Kambula to get there before the Zulu. Wood hurriedly sent a message to Russell, ordering him to move up to the nek but with the advantage of high ground, Russell had already seen the Impi, an hour and a half before Wood and sent a warning to Buller.