It is scarcely necessary to remark that enormous quantities of material were required for the work of the Water-Supply Service, 60 miles of pipe and 300 gas-driven pumps being used during the St. Mihiel and Argonne-Meuse operations alone. As there were not enough Water-Supply troops—the 26th Engineers—for the needs of the army, it was found necessary to supplement their numbers with other Engineer units, motor-truck companies, and pioneer infantry, the Water-Supply Service of the First Army reaching a maximum of 3,500 officers and men. One does not usually associate intelligence work with water-supply, yet the American Water-Supply Service had an intelligence section which was as efficient as that of any branch of the army. Information regarding the water-supply in the territory behind the enemy lines was gathered from all available sources, the _Wasserversorgung_ maps captured from the Germans affording much valuable data, and the information thus obtained was published at frequent intervals, together with maps. The production of these water-maps finally became so highly developed that it was possible for the intelligence section of the Water-Supply Service to place full information at the disposal of the divisional intelligence officers within twenty-four hours after it had been received. So rapid was the American advance in certain sectors that scores of Boche pumping-plants were captured while still in operation, and turned to the task of supplying the thirsty Yanks. I might add that German prisoners, particularly of the corresponding enemy service, frequently were as successfully pumped for information as the wells sunk by the enemy were pumped for water. * * * * *