France was looking with eager eyes toward Texas, in the hope of securing and extending her Mexican usurpation. England was ready to give all the assistance in her power to any step which would weaken the North; and had the rebels been pressed back from the seaports and the Northern Atlantic slope, they would have had it in their power, if still holding the Mississippi, the South-west, including Tennessee, and the great natural fortresses of the mountains, to have so connected themselves with Mexico and France as to have caused the most serious embarrassment. It became absolutely necessary to the success of the Government that the rebels' northern line of defenses should be broken through, and that the Mississippi should be opened to its mouth. At first, and before the nature of the work was fully understood, the whole was placed under the direction of the War Department, as it was thought the few armed transports which would be needed would be a mere appendage of the army. The idea of a formidable river navy of a hundred powerful steamers did not in the beginning enter into the minds of any. It was soon seen, however, that an entirely new description of craft was needed for this work. It was clear that the river boats, which had been built for the common purposes of freight and passage, were not capable of resisting the fire of heavy artillery, and that the batteries of the rebels could not be captured nor even passed by them. They could not even be safely employed alone in the transportation of troops, for they could be sunk or crippled by the field batteries that could be moved from point to point. The question of iron-clads was proposed, but with only the ocean iron-clads as a guide, who should conceive the proper form of an armored boat which could navigate our rivers and compete successfully with the heavy guns, rifled as well as smooth-bore, of the fortifications. It was by no means easy to solve this problem, but it was absolutely necessary that the attempt should be made.... These forts could only be reduced by the aid of gunboats, and these were almost literally to be created.