In 1672 Maximilian Heinrich of Bavaria, the Archbishop and Elector of Cologne pledged Neuss for a large sum of money to France. The French King Louis XIV. was planning an attack on the Protestant Dutch Republic, sought a territorially favorable base for his operations and wanted to develop Neuss into a citadel. The plans for this were drawn up by the French fortress architect Sébastien Le Prestre de Vauban. Against the futile resistance of the people of Neuss, a deep trench is dug around the future citadel, cutting through the city. Large parts of the city wall and numerous buildings have to give way. After the attack on the Netherlands on May 2, 1672, Neuss suddenly lost its strategic importance. In 1672 the town was returned to the Cologne archbishop. Since completing the half-finished citadel would have been too expensive, the ruined building was razed. Today only mounds in the Stadtgarten park bear witness to the planned complex.