The calculated distance (air line) between Düsseldorf and Mourmelon-le-Grand is approximately 180 miles respectively 289 kilometers.
By car or train, the actual journey to Mourmelon-le-Grand is certainly longer, as only the direct route (as the crow flies) between Düsseldorf and Mourmelon-le-Grand has been calculated here.
Air line (approximately)
289 kilometers
156 nautical miles