A ten minutes' walk brought Captain Foster and Hal into Agua Dulce. It was an insignificant little village, of perhaps eight hundred inhabitants. Five hundred of these were Mexicans. There are many such towns on the Texas border. The Mexicans were engaged somewhat in trade, but most of them belonged to the floating class. They were cowboys, sheep-herders and laborers. Few of them represented a high grade of Mexican citizenship. Many were "wanted" in Mexico for minor offenses, for which the extradition treaty did not provide. Living only from day to day, usually from hand to mouth, and nearly always discontented, this sort of Mexican was excellent material out of which to make a revolutionist. "It doesn't look like much of a place for a headquarters against the powerful Mexican government," Captain Foster confided to his young lieutenant. "Yet it is in just such places as this that a successful revolution in Mexico may some day start. It might happen in this year as well as in any other. A few thousand rifles and enough cartridges could be shipped from this point, across the river, on a dark night. With this happening at several such points enough munitions for an Army might be ferried across. With men waiting on the other side a rebel army could be easily started." "It seems a pity, doesn't it, sir, for us to have to interfere in such matters?" asked Lieutenant Hal. "No; for the United States is on friendly terms with the government of Mexico. Therefore, under the laws of nations, we are obliged to see to it that all caution is used to prevent the shipment of arms to revolutionists on the other side of the river. Mexico would have to do as much for us if the case were reversed." "But the case never is reversed," smiled Hal. "It came near being, once. At the outset of the Spanish war, when there were a good many Spaniards living in Mexico, some of them started a foolish movement to organize and project an armed force of Spaniards over the border into Texas. The Spaniards had a notion that they could slip over the border, do a lot of harm and get safely back into Mexico. But the Mexican government sent out its secret service agents to run down the plot, and also sent two or three regiments of the Mexican army to patrol the border." "What did the people of Texas think of that, sir?" Captain Foster laughed. "The Texans were really mad as hornets," he continued. "They said they wished the Mexican government would mind its own business and not spoil sport. The Texans were just aching to have a few thousand Spaniards come over the border and start things going. None of the Spaniards would ever have got back into Mexico; the Texans would have taken care of that. But here we are in the village, and now we'll have to start making inquiries."