Soon after the first shots were fired between the Boers and the British on the 11th October 1899; the repercussions of loyalties were felt in Jansenville.
A number of inhabitants were loyal to the British Government, however, the majority favored the cause of the Boers, with the result that Martial Law was proclaimed, and the town and district came under military occupation set up by Captain Gould.
Little of consequence happened over the next 15 months until January 1901 when the town of Jansenville was abuzz with excitement.
It was on a Sunday in January 1901 that the volunteer Town Guard at Jansenville, supplemented by British troops, all under Captain Gould, began the construction of Jansenville Fort.
The stone fort stands prominently on a hill on the west side of the Graaf-Reinet road on the north of the town.
The Town Guard also erected a blockhouse on a knoll by the bridge over the Sundays River and another at the intersection of Main and Bridge streets, but these have long since vanished.
The remaining fort at Jansenville measures approximately 21m x 15m overall. The outer walls are at a height of approximately 2m, varying in thickness from 800mm to 1200mm, and are provided with tapered loopholes.
The entrance to the fort is at the south-east corner and has a right-angled turn in its passage. In the middle of the fort was a detached block, which formed two rooms or enclosures, both of which could be entered by several doorways, protected externally by curved screen walls, presumably to shield the occupants from possible stray bullets which could have passed through the loopholes in the outer walls. These rooms may have been roofed and could have served as officers’ quarters or as shelters in wet weather.