The calculated distance (air line) between Bonn and Mons-en-Barœul is approximately 174 miles respectively 281 kilometers.
By car or train, the actual journey to Mons-en-Barœul is certainly longer, as only the direct route (as the crow flies) between Bonn and Mons-en-Barœul has been calculated here.
Air line (approximately)
281 kilometers
151 nautical miles