What happened September 1900 AD

By September 1900, the British were nominally in control of both Republics, with the exception of the northern part of Transvaal. However, they soon discovered that they only controlled the territory their columns physically occupied. Despite the loss of their two capital cities and half of their army, the Boer commanders adopted guerrilla warfare tactics, primarily conducting raids against railways, resource and supply targets, all aimed at disrupting the operational capacity of the British Army. They avoided pitched battles and casualties were light.

Roberts declared the war over on 3 September 1900; and the South African Republic was formally annexed.