The next stage was that which saw the slow building up of the blockhouse system and the institution of small punitive columns, and may be considered to have extended until the close of 1901.
The fifth, and last period - which, after all other expedients had failed, finally brought the residue of uncaptured and unsurrendered burghers to submission - was the final development of the blockhouse system, wedded to the institution of systematic. " driving " of given areas, which operations were in force until the 31st of May 1902, when peace was ratified at Pretoria.
The establishment of a line of defensive posts between Bloemfontein and Ladybrand, though De Wet had three times traversed it, had given Blockhouse Policy.
By the end of the year the blockhouse system was complete, but this phase of the war was destined to close badly as De Wet on Christmas Eve captured a large force of Yeomanry at Tweefontein, west of Harrismith.
The blockhouse system was practically finished, and Kitchener determined upon a new means of harassing the enemy, who still had a total of about 25,000 men in the field.
In the past the mobile columns, of which there were over sixty in the field, had always been bound to the railway for supply; now convoys could be pushed out to them along whatever blockhouse line they touched.
This was a blockhouse built for coast defence by Henry VIII., but became the official residence of the Lords Warden of the Cinque Ports, and was in consequence much altered from its original condition.
In 1497 a blockhouse was built at the harbour mouth as a protection against the English.