REVIEW AND ANALYSIS 37 cloud and sea fog were threats to the effectiveness of the system, and some accounts suggest in fact that the stations never operated simultaneously. Following Napoleon’s defeat at Waterloo in 1815, many of these structures were abandoned, as their maintenance was costly. Nevertheless, coastal defences continued to be constructed around the most important naval ports, and in 1859 another threat of invasion, this time under Napoleon III, led the Prime Minister Lord Palmerston to carry out a major review of coastal defences. The report recommended substantial improvements to key installations such as the Royal dockyards, although the grounds for their construction were never substantiated, and these later forts became known as ‘Palmerston’s follies’ when the feared invasion failed to materialise. CONSERVATION With large rooftop areas for surveying the coast, for signalling, and for mounting heavy artillery, the Napoleonic forts are highly exposed to rain and salt-laden sea spray. Flat masonry roofs are far from ideal, even if regularly coated in bitumen. Many are sited close to the sea where they are exposed to the full force of wind and water, and the abrasive forces of sand and small stones that can become airborne in stormy weather. Sea salt adds to the problem, accelerating the corrosion of ferrous metals and causing salt crystallisation issues for porous masonry. Thick coats of lime-render would have helped these structures to dry out, forcing salts to crystallise in this sacrificial layer rather than the brick. Maintenance was therefore important, both to keep the water running off the roof and into the drainage channels, and to maintain the render. While in active service, there was no shortage of labour to keep them well maintained. However once redundant, maintenance became expensive and without regular heating and ventilation, water ingress would have exceeded the rate of drying, so walls would eventually become saturated. Generally, deterioration in these circumstances is relatively slow, particularly if managed with appropriate and targeted maintenance. Coastal erosion and subsidence, however, are more immediate, and in some areas of the country these monuments are particularly vulnerable. Of the 74 Martello towers constructed in Kent and East Sussex, only 26 survive. Keeping historic buildings in use is generally accepted as being the best way to ensure that they are maintained and looked after for future generations. In the absence of any viable alternative, many Napoleonic forts are likely to remain as archaeological sites, cared for by either the state, local government or voluntary bodies such as a preservation trust or civic society. Of the Irish signal towers, the signal tower at the Old Head of Kinsale, County Cork, is probably the only one accessible to the public, having been restored by the local community to include a museum telling the story of the 1915 sinking of the Lusitania, and a memorial garden. The tower itself is just over nine metres high, with walls up to 80cm thick. Records show a signal crew was in place in 1804 and the tower finished the following year, although severely affected by damp. The tower is now a popular tourist attraction on the Wild Atlantic Way, Ireland’s coastal route beginning at the Inishowen Peninsula in the north, down to Kinsale. Patched, repaired and modified gun emplacements at the Needles Old Battery, Isle of Wight. Dating from the early 1860s, this rambling fortification was adapted for use in both world wars and is now cared for by the National Trust.
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