During the war, these patents in the United States were taken over by the Alien Property Custodian, and the American industries that sprung up in consequence may be permanently protected. Other allied countries took the same steps to free themselves from German control, which has retarded the development of the by-product coke industry in non-German countries. In _Germany_ the large mining companies generally own the coal rights. The only government that has mined coal on a commercial scale and for commercial purposes is Germany, and even there the government production covered only a small part of the total output of the German Empire. Mines of the Saar coal field and a group of mines in the Upper Silesian field owned by the Prussian government have been the only extensive state-operated mines of the world, and now, under the terms of the Treaty of Peace, the ownership of the Saar mines will pass to France. (The details are given on p. 39). On the other hand, the government exercised a quiet but real control over the whole German coal industry. Through its ownership of the Koenigen Louise mines it acted as a member of the Upper Silesian coal syndicate. Formerly, through its ownership of the Saar mines, it was also a member of the Westphalian coal syndicate, but whether a member or not it practically approved the syndicate operations and the fixing of prices in advance; also, it co-operated with the syndicate in hauling the latter’s coal over state-owned railway systems. In certain undeveloped coal fields in Germany, the northern extension of the Westphalian field, the Prussian government retains most of the coal rights.