The building of blockhouses started in March 1900 to protect the railways, in particular the railway bridges. Many of these were impressive structures of stone, with corrugated iron roofs, standing three storeys high and enetred by an external wooden stair in the form of a drawbridge.

These were effective but also time consuming and costly to build. This led to more modest style structures being built in the form of rectangular, signle-storey buildings with a stone wall mounted upon which was a coorugated iron upperwork, this was pierced with loopholes and double skinned, the void between being filled with stones to block rifle fire. Even these structures were slow to construct and a solution to these was sort by Kitchener, he turned to Major Spring R Rice, Officer Commanding 23 Field Company, Royal Engineers based as Middleburg, Transvaal.

Major Rice designed two new forms of blockhouse, the first octagonal and the second, the one that became known as the 'Rice Blockhouse'. circular. This was made of of corrugated iron filled with a stone-filled, loopholed shield above and an earth-filled caisson below, the whole being topped off with a stone roof. When ideally sited the door was blocked approached under cover of a trench and the hillock on which it sat and the lower part of the walls was covered with loose stones for added protection. It was said that trained men could erect such a blockhouse in a single day and the record for erecting one was a mere three hours. It was usually garrisoned by a non-commissioned officer and six men. Outside the immediate area was protected by barbed wire and a barbed wire fence stretched between one blockhouse and the next, hung out with tin cans to make as much noise as possible when disturbed.

The fortifications in cluded numerous other modesl, often ad-hoc designs fashioned to meet the requirements of the location and adjusted to make the best of available materials, but the Rice design was the one that sprang up in huge numbers. By September 1901 the Western Railway blockhouse line from De Aar to Lobatsi, north of Mafeking, was complete, as was the Central Railway system from Naauwpoort to Pretoria and the Delalgoa Railway to the border of Koomati Poort. In addition a box west of Johannesburg and Pretoria and a line south-east to Standerton and Newcastle were operational. In the next three months the line north from Pretoria to Pietersberg was built, the Western Railwasy cover extended south-west to beaufort West and numerous additions made in Transvaal and was now Orange Colony. By May 1902 a line of blockhouses ran from Beaufort West right across Cape Colony to the Atlantic coast and yet more lines had been added elsewhere. By the end of the war there were 3,700 miles (6,000km) of lines with some 8,000 blockhouses manned by 50,000 British troops and 16,000 Africans.

Source: The Boer War South Africa 1899-1902 by Martin Marix Evans