Cherbourg Harbour

Cherbourg Harbour (French rade de Cherbourg; literally, the roadstead of Cherbourg), is a harbour situated at the northern end of the Cotentin peninsula, on the English Channel coastline in northwestern France. With a surface area of 1,500 hectares, it is the second largest artificial harbour in the world, after the 4,500 hectare Ras Laffan Harbour in Qatar. Cherbourg has been used for mercantile shipping as well as a naval base.

It was begun in 1783, with its central harbour wall completed in 1853 - this was 3.64 km long, an average of 100m wide at its base and an average of 12 m wide at its top, and sited 4 km from the coast. Three forts were added to the central wall in 1860. This and the two other harbour-walls stretch for more than 6 km. The eastern opening into the harbour is 950 m wide and the western one 2.3 km wide. The harbour's maximum depth is 13 m at low tide.

Cherbourg had been a strategic stronghold for several centuries - its castle was first built in the 5th century to protect the whole width of the Cotentin. In the 17th century Vauban, Marshal of France, launched a project to fortify the town, but they were finally razed shortly afterwards. In 1692 several naval ships under Amiral de Tourville put into the port at Cherbourg after the opening battle of the Battles of Barfleur and La Hogue—the port's lack of adequate defences were revealed when fire ships destroyed many of the French ships under repair, including Le Triomphant at the entry point into the port, L'Admirable on the Mielles, and the Soleil Royal, the admiral's flagship, on the pointe du Hommet.

The long-planned fortification of the town was finally set in motion by Louis XVI of France. In 1776, he set up a commission to choose between Cherbourg, Ambleteuse or Boulogne as France's main strategic port for defence of the English Channel - this was headed by Suffren and also including Dumouriez (later governor of Cherbourg) and La Bretonnière. La Bretonnière's report considered that only Cherbourg had a harbour large enough for 80 warships at once. Exceeding Vauban's designs, he planned the construction of a 4 km long harbour wall between île Pelée and pointe de Querqueville. Dumouriez and Decaux, head of the engineers, advised that Louis build a shorter harbour in a straight line between île Pelée and pointe du Hommet, as foreseen by Vauban, with a single central entry point, with the emphasis on military defences. In the end La Bretonnière's plan won, but during the construction phase Decaux argued for the merits of concrete masonry caissons whereas La Bretonnière preferred sinking old warships and building up rock around them. However, the engineer Louis-Alexandre de Cessart's plans were chosen, which involved constructing a mole from 90 tree trunks 20m by 20m, filled in with stones and linked by iron chains.

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