 Whereas de la Rey and Smuts were wildly successful in their region, Botha and Hertzog (leading the two largest armies) found it difficult to replicate the tactics and success of their compatriots.Gradually, the British built a system of forts, concentration camps, and armed patrols, and cut the country up with great lines of barbed wire and trenches.As it became harder to evade their armies, the Boers ran out of success.