On the 5th Ermelo was occupied, and the fresh deep ruts upon the veld told the British horsemen of the huge Boer convoy that was ahead of them.

For days enormous herds, endless flocks, and lines of wagons which stretched from horizon to horizon had been trekking eastward.

Cavalry and mounted infantry were all hot upon the scent.
Botha, however, was a leader of spirit, not to be hustled with impunity.
Having several thousand burghers with him, it was evident that if he threw himself suddenly upon any part of the British line he might hope for a time to make an equal fight, and possibly to overwhelm it.

Were Smith-Dorrien out of the way there would be a clear road of escape for his whole convoy to the north, while a defeat of any of the other columns would not help him much.

It was on Smith-Dorrien, therefore, that he threw himself with great impetuosity.