What is recorded here

Knocknagarhoon Castle was a two-storey signal tower completed by 1805 to warn Ireland of a French invasion fleet, standing on a small Clare hill with distant views in every direction. The British Board of Ordnance built it as one link in a coastal chain stretching from Dublin Bay to Malin Head, using naval signal posts to pass urgent news between stations. Men may have watched the sea for months before returning to ordinary life when the danger faded. Its stones were later removed for elsewhere, leaving only a shallow earthen ring and scattered rubble where the watchroom once stood.

Situated on the top of a small hill overlooking the coastline located 440m to the NW (126m OD). Located on a level area with gentle slopes to the NW and SE, and with distant views in all directions. The surrounding area consists of enclosed pasture defined by linear rubble stone walls and earthen banks. There is a small area of quarrying within 12m of the NNW edge of the site. The adjacent towers in the signal tower chain are found at Loop Head (CL071-043----), located c. 12.4kms to the SW but now demolished, and at Ballard (CL046-005----), located c. 14.3kms to the NE, also now demolished. Site of signal tower at Knocknagharoon is located c.2.1kms NNW of a bivallate ringfort (CL065-041----) at Killinny that is indicated as ‘Lisnagreeve’ on the Ordnance Survey third ed. six-inch map of c. 1913-7 and c. 4.7kms WSW from Kilcasheen Graveyard (CL065-026----). The site of an early nineteenth-century (c. 1804-5) originally two-storey square-plan signal tower (approx. ext. dims. 5.85m NE-SW x 5.85m NW-SE), built with roughly coursed rubble. The signal station has collapsed or has been demolished, and the stone masonry has been removed from the site for use elsewhere. A disturbed overgrown semi-circular area of ground (int. dims c. 5.8m E-W x c. 5m N-S) indicates its former position. This semi-circular area is enclosed by an earthen bank (Wth c.2.4 to c. 3.8m; H c. 0.3m to 0.6m) and contains some stone rubble. This area is unenclosed to the S. Kerrigan established that the signal tower was completed by 1805 (Kerrigan 1995, 278). The Ordnance Survey first ed. six-inch map, surveyed 1840-2, shows a small square building identified as ‘Knocknagharoon Castle (in Ruins)’ located inside a circular enclosure. The signal tower and the enclosure are no longer visible on the Ordnance Survey second ed. six-inch map, surveyed 1893-7, suggesting the site had been cleared by this time. The signal tower was part of a system of over 80 signal stations constructed by the British Board of Ordnance in the first decade of the nineteenth century to warn of the approach of a French invasion fleet. Signalling between sites was accomplished using a naval signal post. The system formed a continuous chain from Dublin Bay running clockwise all the way around the coast to Malin Head in County Donegal. It was abandoned by the mid-1810s when the threat of a French invasion diminished (Kerrigan 1995, 157-66). Compiled by: Stuart Rathbone Uploaded on: 14/07/22

This remains an important historical record, but the official description says the monument is no longer visible or has been destroyed. The monument record does not grant public access. Check the route and ask the landowner before entering private land.