that there was no threat from France and those who believed that greater security should be achieved by further spending on the navy. The chief opponents were the Radical Richard Cobden and his ally, William Ewart Gladstone, then Chancellor of the Exchequer, who between them had recently concluded the Cobden–Chevalier Treaty, a Free Trade agreement with France. The bill was accepted as the Fortifications (Provisions for Expenses) Act 1860, providing an initial sum of two million pounds and later payments financed by loans to a total of nine million. By the time the fortifications were completed in the 1880s it was clear that the French had not seriously planned to invade. The Franco-Prussian War of 1870–71 removed the threat and the forts became known as Palmerston's Follies. As a key purpose of fortification is deterrent, this judgement was harsh, but with the rapid development of warship design during the period, the time taken to plan and implement the works would always have caused problems with ensuring that the defences were capable of defeating a French attack force. The works The types of fortification constructed as a result of the Royal Commission fell into two main categories; coastal batteries and land forts. Coastal batteries The main purpose of the coastal batteries was to provide protected positions for heavy coastal artillery which would be able to engage enemy warships and troopships. In some places, for instance high on a cliff, the guns could be mounted in a barbette or open gun pit. However where the batteries were close to the shoreline and could be engaged directly by enemy gunfire, each heavy gun was mounted in a casemate, a vaulted chamber with embrasure for the gun to fire through which was pierced through an armoured shield. Since being mounted in an enclosed space limited the traverse of the gun, casemates were arranged in a long curved row so that the guns of the battery could follow the progress of a passing enemy ship, each weapon engaging it in turn. The rear of the battery was closed either by a simple wall pierced with loopholes, or by a more elaborate defensible building which doubled as a barracks for the garrison. The intention of these rearward defences was that they would be strong enough to prevent the battery being taken by enemy infantry but weak enough to be demolished should the battery fall into enemy