The stronger party, if it be wise, leaves the entrenchments alone and uses its strength to go round them.

Lord Roberts meant to go round.

With his immense preponderance of men and guns the capture or dispersal of the enemy's army might be reduced to a certainty.

Once surrounded, they must either come out into the open or they must surrender.
On March 6th the cavalry were brought across the river, and in the early morning of March 7th they were sent off in the darkness to sweep round the left wing of the Boers and to establish themselves on the line of their retreat.

Kelly-Kenny's Division (6th) had orders to follow and support this movement.