The American official campaign historian, Martin Blumenson, notes that Bradley, impressed, ordered the device be manufactured in quantity. Initially this was done using steel salvaged from the thousands of obstacles, such as Czech hedgehogs, that the Germans had placed on the French beaches during the construction of the Atlantic Wall. Bradley also dispatched Colonel John Medaris (of the Ordnance Department) back to the United Kingdom to have tanks modified before being shipped to France, and arranged for additional arc welding equipment and crews to be transported to France by air.