That, in itself, is part of the interest. A signal station was built here by 1804, its mast erected by 1805, and it formed one link in a chain of over eighty such stations constructed by the British Board of Ordnance along the Irish coastline to give warning of an approaching French invasion fleet. The chain ran continuously from Malin Head in Donegal down to Dublin Bay, with each station using a naval signal post to pass messages along the line. The Crossfarnogue station sat between a station at Baginbun to the west, where the signal crew were housed in a Martello tower, and one at Hilltown to the north-east, now also gone. By the time the threat of French invasion had faded in the mid-1810s, the whole system was abandoned.

What makes Crossfarnogue unusual even within this largely vanished network is how early it disappeared. When the Ordnance Survey carried out its first detailed six-inch mapping of the area in 1839 to 1840, the station was already gone, leaving no trace on the record. Its exact location and original form remain uncertain; the most likely position is somewhere on the centre of the peninsula, a short distance north-north-east of Forlorn Point, though one researcher has suggested it may have stood closer to Kilmore Quay itself, possibly on a site that was later occupied by a coastguard station. Across the water in Waterford, five of the six signal towers in that county were also demolished early, and a probable reason survives in a written complaint from 1811. A Mr. Pope, Waterford Agent of the London Assurance Company, wrote to warn that derelict signal towers along the Waterford coast were being mistaken for lighthouses by mariners in poor weather, contributing to a series of shipwrecks near Tramore around 1810. His concerns appear to have been acted upon; a station near Tramore, probably at Brownstown Head, was pulled down by the end of 1811. It is plausible that the Crossfarnogue station was taken down around the same time and for the same reason, a structure built to protect ships from enemy action quietly removed because its empty shell had begun to sink them.