railway guns, six K5 guns and a single K12 gun with a range of , could only be used against land targets. The remainder, thirteen guns and five guns, plus additional motorised batteries comprising twelve guns and ten guns, could be fired at shipping but were of limited effectiveness due to their slow traverse speed, long loading time and ammunition types. Land-based guns have always been feared by navies because they are on a stationary platform and are thus more accurate (and can be larger, with more ammunition stowage) than those on board ships. Super-heavy railway guns can only be traversed by moving the entire gun and its carriage along a curved track, or by building a special cross track or turntable. This, combined with their slow rate of fire (measured in rounds per hour or even rounds per day), makes it difficult for them to hit moving targets. Another problem with super-heavy guns is that their barrels (which are difficult to make and expensive to replace) wear out relatively quickly, so they could not be fired often. Better suited for use against naval targets were the four heavy naval batteries installed by mid-September: Friedrich August, Prinz Heinrich, Oldenburg and Siegfried (later renamed Todt) – a total of eleven guns, with the firepower of a battlecruiser. Fire control for these guns was provided by both spotter aircraft and by DeTeGerät radar sets installed at Blanc-Nez and Cap d’Alprech. These units were capable of detecting targets out to a range of , including small British patrol craft near the English coast. Two additional radar sites were added by mid-September: a DeTeGerät at Cap de la Hague and a FernDeTeGerät long-range radar at Cap d’Antifer near Le Havre. The longest-ranged guns were Kanone 12 in Eisenbahnlafette, manned by the Heer. These guns had an effective range of . Designed as successors to the World War I Paris gun, they had a maximum range of . Shell fragments were found near Chatham, Kent, about from the French coast. Both guns, which were operated by Artillerie-Batterie 701 (E), remained on the Channel Coast until the Liberation of France in July 1944. Most of the batteries continued firing until September 1944 when they were overrun during the clearing the Channel Coast. By then more than a thousand rounds had been fired by the German coastal batteries against England and shipping. The only two vessels to