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Origin and history

The south lock bridge of the Yutz crown, located in Thionville in the East, is part of an innovative defensive system developed in the 18th century. Built between 1746 and 1752 under the direction of engineer Louis de Cormontaigne, it was designed to drift the waters of the Moselle to protect the city from flooding while serving as a defence mechanism. This canal, equipped with two lock bridges (north and south), allowed to flood the valley in case of attack, a technique popularized by Vauban from the seventeenth century.

The southern lock bridge, the only one remaining today, is a remarkable example of the military architecture of the time. With six arches in basket handle and square piles, it incorporated wooden grids and valves to control water flow. At the first level, a "test" store stored wartime supplies, while the second level provided storage space for peace periods. Although partially damaged in the 20th century (especially in 1962 during work on the Moselle), it was restored and classified as a Historic Monument in 1984.

This system is part of a tradition initiated by Vauban, who had already experienced lock bridges in Verdun (from 1680), Metz, Strasbourg, and Mainz. The first flood test in the presence of Louis XIV took place in Verdun in 1687, validating the effectiveness of this device. In Thionville, Cormontaigne adapted this principle by adding a flood control function, illustrating the evolution of fortifications towards dual-use structures, both civilian and military. The south lock bridge, now owned by the commune, bears witness to this hydro-military engineering characteristic of the Enlightenment century.

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