The military front stretched east and west across the border States from the Mississippi Valley to the sea. This immense and fluctuating front, under its various and often changed commanders, was never a well coordinated whole. The Alleghany Mountains divided the eastern or Virginian wing from the western or "River" wing. Yet there was always more or less connection between these two main parts, and the fortunes of one naturally affected those of the other. Most eyes, both at home and abroad, were fixed on the Virginian wing, where the Confederate capital stood little more than a hundred miles from Washington, where the greatest rival armies fought, and where decisive victory was bound to have the most momentous consequences. But the River wing was hardly less important; for there the Union Government actually hoped to reach these three supreme objectives in this one campaign: the absolute possession of the border States, the undisputed right of way along the Mississippi from Cairo to the Gulf, and the triumphant invasion of the lower South in conjunction with the final conquest of Virginia.
We have seen already how the Union navy, aided by the army, won its way up the Mississippi from the Gulf to Baton Rouge, but failed to secure a single point beyond. We shall now see how the Union army, aided by the navy, won its way down the Mississippi from Cairo to Memphis, and fairly attained the first objective--the possession of the border States; but how it also failed from the north, as the others had failed from the south, to gain a footing on the crucial stretch between Vicksburg and Port Hudson. One more year was required to win the Mississippi;two more to invade the lower South; three to conquer Virginia.
Just after the fall of Fort Sumter the Union Government had the foresight to warn James B. Eads, the well-known builder of Mississippi jetties, that they would probably draw upon his "thorough knowledge of our Western rivers and the use of steam on them." But it was not till August that they gave him the contract for the regular gunboat flotilla; and it was not till the following year that his vessels began their work. In the meantime the armies were asking for all sorts of transport and protective craft. So the first flotilla on Mississippi waters started under the War (not the Navy) Department, though manned under the executive orders of Commander John Rodgers, U. S. N., who bought three river steamers at Cincinnati, lowered their engines, strengthened their frames, protected their decks, and changed them into gunboats.
The first phase of the clash in this land of navigable rivers had ended, as we have seen already, with the taking of Boonville on the Missouri by that staunch and daring Union regular, General Nathaniel Lyon, on June 17, 1861. Boonville was a stunning blow to secession in those parts. Confederate hopes, however, again rose high when the news of Bull Run came through. At this time General John C. Fremont was taking command of all the Union forces in the "Western Department," which included Illinois and everything between the Mississippi and the Rockies. Fremont's command, however, was short and full of trouble. Round his headquarters at St. Louis the Confederate colors were flaunted in his face. His requisitions for arms and money were not met at Washington. Union regiments marched in without proper equipment and with next to no supplies. There were boards of inquiry on his contracts. There were endless cross-purposes between him and Washington. And early in November he was transferred to West Virginia just as he was about to attack with what seemed to him every prospect of success. He had not succeeded. But he had done good work in fortifying St. Louis; in ordering gunboats, tugs, and mortar-boats; in producing some kind of system out of utter confusion,; in trusting good men like Lyon; and in sending the then unknown Ulysses Grant to take command at Cairo, the excellent strategic base where the Ohio joins the Mississippi.
The most determined fighting that took place during Fremont's command was brought on by Lyon, who attacked Ben McCulloch at Wilson's Creek, in southwest Missouri, on the tenth of August.
Though McCulloch had ten thousand, against not much over five, Lyon was so set on driving the Confederates away from such an important lead-bearing region that he risked an attack, hoping by surprise, skillful maneuvers, and the help of his regulars to shake the enemy's hold, even if he could not thoroughly defeat him. Disheartened by his repeated failure to get reinforcements, and very anxious about the fate of his flanking column under Sigel, whose attack from the rear was defeated, he expressed his forebodings to his staff. But the light of battle shone bright as ever in his eyes; he was killed leading a magnificent charge; and when, after his death, his little army drew off in good order, the Confederates, by their own account, "were glad to see him go."On the twentieth of September the Confederates under Sterling Price won a barren victory by taking Lexington, Missouri, where Colonel James Mulligan made a gallant defense. That was the last Confederate foothold on the Missouri; and it could not be maintained.