However, the Franco-Prussian war of 1870 destroyed the velocipede market in France, and the "bone-shaker" enjoyed only a brief period of popularity in the United States, which ended by 1870. There is debate among bicycle historians about why it failed in the United States, but one explanation is that American road surfaces were much worse than European ones, and riding the machine on these roads was simply too difficult. Certainly another factor was that Calvin Witty had purchased Lallement's patent, and his royalty demands soon crippled the industry. The UK was the only place where the bicycle never fell completely out of favour.