The calculated distance (air line) between Dortmund and Ars-sur-Moselle is approximately 179 miles respectively 288 kilometers.
By car or train, the actual journey to Ars-sur-Moselle is certainly longer, as only the direct route (as the crow flies) between Dortmund and Ars-sur-Moselle has been calculated here.
Air line (approximately)
288 kilometers
156 nautical miles