Headscratchers / The Defence of Duffer's Drift

• How do the Boers get across the river when there is only one guarded crossing? In the first dream, they are practically in the camp before being spotted, and in later ones they are firing on the British trenches from Waschout Hill behind them. The river in the map looks more like a canyon and in later dreams the British are alert and should be able to see them crossing (by wading? laborious climbing?), yet it is never mentioned.