"Hold on, major, somebody is coming," interrupted Ben, and pulled his companion back. He had seen a faint light advancing toward them, from a side road which joined the main road at a point but a few yards distant. Soon he made out a heavy cart approaching, drawn by a pair of caribaos, or water buffaloes. On the seat of the cart sat two sleepy-looking natives. "We must stop that cart," was the major's comment. "If we don't, there will be a bad smash-up." "I don't think it's a good plan to expose ourselves," replied Ben. "But do you want those chaps to break their necks?" demanded the commander of the first battalion. "More than likely they are _amigos_." "I've got a plan for warning them, major." As Ben spoke he picked up some of the driest of the grass and palm leaves and applied a match to the stuff. It blazed up readily, and he threw the mass in with the other stuff about the edge of the hole. "There, if they can't see that they must be blind," he said. "Come, let us get out," and off they ran for the thicket close at hand. From here they watched the cart and saw it come to a halt near the hole and knew that the turnout was safe. "I shouldn't think the rebels would care to leave those holes about," was Major Morris' comment, as they pushed on once more. "They are as dangerous to their own people as they are to us." "I suppose they tell their own people about them." "Those men on the buffalo cart evidently knew nothing." "The rebels don't care for the _amigos_. Their idea is, if a native is not with them, he is against them, and must suffer with the Americans." To play the part of spies in such a country as this was not easy, for the Americans were easily distinguished from the natives. Had Ben and the major spoken Spanish fluently, they might have passed for Spaniards, as each was tanned from constant exposure to the strong sun. But this could not be, and so they had to go ahead and trust to luck to see them through with their dangerous errand. At length they felt that they must be close to the enemy's picket line, and paused to consider the situation. Before them was a gentle slope, terminating at a small but deep stream which flowed into the Rio Grande River. "I think some of the rebels are over there," said the major, pointing to a hill, from the top of which could be seen a faint glow. "There is certainly a camp-fire back there." "There is a house just below us," returned Ben. "Or is it a mill?" "A mill most likely. They wouldn't build an ordinary dwelling right at the water's edge." "Perhaps the rebels are using the mill as a sort of headquarters. What do you say if we investigate?" The major agreed, and they began to pick their way along the stream. Soon they reached a rude bridge, and were on the point of crossing, when a sharp cry rang out from the building they were approaching. "Hullo, that's a woman's voice!" exclaimed Ben. "Somebody is in trouble."