Four Lighthouse

Timeline

Heritage classified

Key figures

Origin and history

The Four Lighthouse, located off the Croisic on the Four plateau, is the first offshore lighthouse built in France. Its construction, initiated by engineers Joseph Marie Rapatel and François Plantier, began in 1816 and was completed in 1821, with commissioning in January 1822. With an initial height of 17 metres, it was increased by six metres in 1946 and automated in 1983. Its spiral pattern serves as a bitter for navigation.

The lighthouse was erected on a dangerous pitfall, pointed out in 1810 by the engineer Plantier as a major risk for sailors entering the Loire estuary. The decision to build in the open sea, inspired by the British lighthouses of Eddystone and Bell-Rock, aims to demonstrate French ingenuity. The granite masonry cylindrical tower, with an oak wheelbase for stability, was added in 1819 to the contractors Dardel and Genton.

In 1846, the lighthouse was enhanced and equipped with a retro-reflector, while an access pier was completed in 1886. Its fire, initially fed with vegetable oil (1822), went on to mineral oil (1875), then oil (1904). In 1932, a mercury tank and modern optics were installed. Ranked a historic monument in 2012, it symbolizes technical innovation and French maritime history.

The Four Lighthouse is represented in 2019 on a French postage stamp from the Repères series of our coasts, highlighting its heritage importance. Today, it is remote controlled and unguarded, but its interior is deteriorating despite a good exterior. The current aluminium lantern has a 0.15 m focal lens with a range of 19 miles.

The construction of the lighthouse responds to an urgent need to secure navigation, as evidenced by repeated requests from the Nantes Chamber of Commerce in 1815. Although criticized as soon as it was activated for its limited utility by Beautemps-Beaupré, it remains a major architectural prototype, copied on the most advanced British models of the time.

Its history also reflects the geopolitical stakes of the time, as the war with England delayed its construction. The Direction des Ponts et Chaussées sees it as an opportunity to show the French technical power, despite high costs and cheaper terrestrial alternatives.

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