As to the A. E. F.’s own 65,000 tons of loaded shell, it was decided to destroy all gas shell and all explosive shell and cartridges loaded with explosives of doubtful stability and to return the rest to the United States. The work of shipping the serviceable ammunition home actually started, but it went on slowly because of the lack both of labor and of ammunition ships. A fire destroyed one of the three collection dumps in the Château-Thierry area. As the ships repatriated the A. E. F. at a faster and faster rate, the various army areas were evacuated one by one, but it was necessary to leave guards behind at the various ammunition dumps. Then the War Department began studying the problem with a practical eye. Nearly all this ammunition was “war quality”: good enough for rapid consumption on the field, but made hurriedly by inexperienced labor under conditions that made its permanent stability questionable. It was found to be impossible to separate the better ammunition from that of doubtful stability. It was conceded that under ideal conditions this ammunition might be stored safely for five years. Some of it had already been stored for eighteen months; it would take at least a year to transport it all to the United States; and therefore in this country it would be good for only a brief time. Accordingly the A. E. F. authorities negotiated with the French to assume liability for the ammunition, and it all went into the general settlement of 1919 with the French, but as an American liability reducing the financial liability of the French under the agreement. The chief permanent benefits accruing to the United States from its extensive war industry engaged in the manufacture of instruments for sighting and controlling the fire of field guns were (1) a reserve of optical instruments of the most advanced types, some of which had previously been produced only by the French, (2) a large collection of machinery for making these and similar instruments, and (3) an optical glass industry more than sufficient to the normal needs of the country. Before 1914 little, if any, optical glass had been produced in the United States. In demobilizing this industry, the Ordnance Department took care that all these military assets were properly fitted into the preparedness plan. Again we see at work the policy of centering future production in an arsenal. Frankford Arsenal was designated as the military center for fire-control instruments, and here were brought the reserves of materials and tools acquired by the Government in the course of the enterprise.