The octagonal north tower was the combined work of architects Ulrich Ensingen (shaft) and Johannes Hültz of Cologne (top). Ensingen worked on the cathedral from 1399 to 1419, taking over from Claus von Lohre, and Hültz from 1419 to 1439, completing the building at last. The building of the second tower was often discussed, and was seriously proposed when Alsace became part of Germany after the 1871 French-German War in 1871, but was coldly received by the population of Strasbourg, who considered it would be a symbol of German occupation.