The first blockhouses were built on the orders of the British Commander-in-Chief, Field Marshal Lord Roberts in 1900. The main aim of the blockhouse was to protect the railway lines, which were the main supply route for the British army. These blockhouses were two storey constructions built with stone. The entrance to the structures was through a door on the first floor, seven to eight feet off the ground, which was made accessible with a ladder. Each blockhouse cost between 800-1,000 pounds and took approximately three months to build. These blockhouses were extremely effective as not one bridge near them was blown, as was the practice of the Boer forces. The Witkop Blockhouse is an example of this type of blockhouse. In the Eastern Transvaal smaller blockhouses were built from corrugated iron.
As the Anglo-Boer War progressed the Boer forces launched the phase of guerilla tactics (the first time that this sort of warfare had been employed), which made it more complex for the British troops to bring them to battle. Lord Milner, the British High Commissioner of the Cape, suggested extending the line of blockhouses away from the railway lines and building them across the veldt to literally fence the Boers in. A cheaper, easily constructed blockhouse was designed to make this plan practical. These blockhouses were also made from corrugated iron and were round, making it even easier to construct in the shortest time; six hours to be exact!
To protect the blockhouses from possible attack a low stone or sandbag wall was built around it and a trench was dug. Wire entanglements were twisted together and anchored around the forts to make it even more tricky for the Boers to get near. Bells and tins were connected to the wire to act as alarms. A blockhouse was always built on a rise so that the troops could survey the surrounding area. The blockhouse was a successful strategy in that aided in the surrender of the Boers.
The Witkop blockhouse is situated on the R59, near the Engen garage (Traveling South from Johannesburg). It is one of only fifty blockhouses left in the country.