I want to know the answer to the following question:
On what date was the encirclement of Paris complete?
All the background I'm provided with is that "Bismarck met Favre on 18 September at the Château de Ferrières and demanded a frontier immune to a French war of revenge, which included Strasbourg, Alsace and most the Moselle department in Lorraine of which Metz was the capital.". Is that enough to answer the question?