"Now, my work is cut out for me," he told himself. "I can do only one man's part in this war, but I must do that to the limit and try to make the world a safe place of residence for that little woman and all others like her!" No sooner was the "Grigsby" in port, the next forenoon, than Lieutenant Fernald came ashore and straight to the hospital. "Going on board today, sir?" was Fernald's greeting. "You couldn't keep me ashore any longer," Darrin declared. "Good enough!" said the executive officer, heartily. "We need you, sir! We've been doing our best, but the enemy has been gaining on us. Last night two ships struck mines and went down before rescue could reach them. The Germans are beating us at this mine game, and something must be done, which, of course, sir, is another way of saying that a way must be found to do the right and necessary thing." "I've been thinking that over for twenty-four hours," Darrin went on. "As soon as we are aboard I want to talk the whole situation over with you. Will Dalzell be in today?" "In about an hour, sir, I think. He needs fuel and some food supplies." "Then we'll hold a council of war in the chart-room," Dave decided, as he buttoned up his coat. "I'm ready, Fernald." Dave had already thanked the hospital authorities, and taken leave of them, so the two young naval officers passed outside, made their way down to the water front, and soon thereafter stepped aboard the "Grigsby," reporting their arrival on board to the watch officer. Dave also saw that the forward gun damaged in the fight with the German destroyers had been replaced by a new one. From the gangway they went direct to the chart-room. "I'll hear the reports on the work now, Fernald," Dave announced. Two of the papers that came under Dave's hand especially interested him. One was a detailed list of the ships that had struck mines during the last week in the waters in which he and Dalzell had been operating. The other document contained a report on the discovery and sinking of one fighting submarine and one submarine mine-layer. From these reports Dave turned to the charts of the local waters. When Fernald came back with Dan Dalzell, Dave was still poring over the charts. "From the rapid way in which German mines are being planted in these waters," Dave told his brother officers, "I am satisfied that the enemy submarines do not usually go all the way back to the base port. I believe that the mine-layers are often met by other craft that supply them with mines, and that the submarine mine-layers return quickly to the job of planting mines. Now, the sea area in which the mines are planted leads me to feel certain that the mine-layers rest frequently on these three shoals." Dave pointed on the chart to the shoals in question. "How many mine-sweeping craft have we now under our orders?" he inquired. "Nine," said Dan, promptly. "How many of them can we spare from mine-sweeping?" "None," Dalzell replied, positively.