The calculated distance (air line) between Bonn and Montignies-sur-Sambre is approximately 116 miles respectively 187 kilometers.
By car or train, the actual journey to Montignies-sur-Sambre is certainly longer, as only the direct route (as the crow flies) between Bonn and Montignies-sur-Sambre has been calculated here.
Air line (approximately)
187 kilometers
101 nautical miles