For artillery there were the 21st, 42nd, and 53rd batteries of field artillery, and No.

10 Mountain Battery, with the Natal Field Artillery, the guns of which were too light to be of service, and the 23rd Company of Royal Engineers.

The whole force, some eight or nine thousand strong, was under the immediate command of Sir George White, with Sir Archibald Hunter, fresh from the Soudan, General French, and General Ian Hamilton as his lieutenants.
The first shock of the Boers, then, must fall upon 4000 men.

If these could be overwhelmed, there were 8000 more to be defeated or masked.
Then what was there between them and the sea?
Some detachments of local volunteers, the Durban Light Infantry at Colenso, and the Natal Royal Rifles, with some naval volunteers at Estcourt.

With the power of the Boers and their mobility it is inexplicable how the colony was saved.