"Dose craters should of be put in de smoke ball and dropped by a bomb yet!" declared Iggy. "That's right, old scout!" exclaimed Jimmy. "Only don't call 'em 'craters,' Iggy, lad. You're thinking of a shell-hole. 'Traitors' is the word," and he spelled it. "I of thankfulness to you am," said Iggy. "English, she is of mos' queer talk to learn, but I will on keep." "Only way to do!" said Jimmy. The information he had given his chums they soon verified by hearing the talk in and out of the trenches of the disaster of the previous night. That the American plans had been betrayed by someone within the Allied lines was evident. In no other way could the Germans have known that the supporting reserves had been withdrawn. And because of the demoralization caused by the success of the German raid it was impossible, for the time being, to go on with the plans of using the massed reserves, as had been hoped. That afternoon, following mess, when Roger and Bob were on their way to the rear with a message to headquarters they met Captain Dickerson. He was in company with other officers attached to the secret service, and as the captain, who had once been suspected by the boys of being a spy, passed them he acknowledged their salute and paused to speak to them. "I was wondering if we had any trace of them, sir?" said Bob, suggestively. "Trace of whom?" inquired the captain with a good-natured smile. "The fellows who sent signals from our lines and brought on the raid last night," said Roger. "Oh, so you've heard that story, too?" asked the captain. "Isn't it true?" "Well, I'm not going to deny or affirm it," said Captain Dickerson, with a half smile. "But you boys seem to have luck in digging up mysterious matters, so if you hear of any bunch of fellows acting in a queer way or having certain chemicals in their possession you might let me know." "We will, sir!" promised Bob, and Roger nodded his assent. "I'll say this much," went on the captain. "The secret service department is working hard to locate the place where the signals came from, and trying to discover who sent them--if any were sent." The secret service official added this in order to be in conformity with his former statement of not admitting anything. "We'll be on the watch as best we can," promised Roger. Captain Dickerson walked on with other officers from the secret service department of the army, and Bob and Roger regarded each other with serious eyes. "There's more to this than appears," declared Roger. "I believe you," agreed his chum. And in the days that followed they learned this more fully. For the location of a number of American batteries and machine gun nests was, in some manner, disclosed to the enemy. In consequence there was a shelling of these spots by the Germans, and considerable damage was done.