or result from the war, this line of defence along the Sierra Madre would be absolutely necessary to the planting States, as slavery could not be maintained with the Rio Grande as the boundary. In my opinion, the only real advantage which will be gained by this extension of our territory, will be the navigation of the Rio Grande, which will open a trade with the Internal Provinces capable of vast extension. Few southern planters would run the risk of taking their slaves west of the Rio Grande, even with the Sierra Madre as the boundary. They would, of course, migrate in single families, and their negroes could escape, if they thought proper, as fast as they came. I have no doubt, many of them would remain of choice, with their owners; but they would be insecure as property, and that would discourage the importation. The navigation of the Rio Grande is capable of great improvement, and it is ascertained that there is an abundance of coal on its banks. These banks will, some day, be crowded with towns and cities, and their fertile soil will support as large a population as the Nile. Footnote 2: General Wool marched from Paras to Saltillo. There are but two roads by which the city of Mexico can be approached by our invading armies. The first is, from Saltillo, through the populous States of Zacatecas, Guadalajara, Guanahwato, San Louis, and Queretaro, containing near four millions. Now, is it probable, that these States will offer no resistance to the long march of General Taylor at the head of a handful of men? I do not doubt, but that in the open field, at the head of ten thousand men, he would beat three times that number; but the heavy loss sustained at Monterey must satisfy us that such victories will be dearly bought. It cannot be said that the Mexican soldiers have not fought, and on some occasions, have not fought well, and they may learn to fight better. But let us consider again, what an immense commissariat must accompany an army on such a march, to afford the necessary supplies. Those who are urging the march of General Taylor on Mexico, are, perhaps, not as well acquainted as he is with what is necessary for such an undertaking. The second road is from Vera Cruz, the distance of three hundred miles, through a thickly settled country, but with numerous defiles, and where there must be fighting at every step. Vera Cruz may be taken, and will be taken, and then the Castle will fall. Here will be a depot to supply the invading army as it shall advance, step by step; and is it likely we can land an invading army of sufficient strength to crush the forces of the Republic under Santa Anna? If the Mexicans make but an indifferent use of the means in their power, it would seem to me impossible for us to