[Illustration: SECTION OF THE MISSISSIPPI RIVER. SHOWING THE DISTANCES FROM NEW ORLEANS, AND THE ISLANDS BY THEIR NUMBERS. ] [Illustration: SECTION OF THE MISSISSIPPI RIVER. SHOWING THE DISTANCES FROM NEW ORLEANS, AND THE ISLANDS BY THEIR NUMBERS. ] CAIRO. The most important strategic point in the West at this time was the city of Cairo, situated at the extreme southern point of the State of Illinois, at the junction of the Ohio and Mississippi rivers, where the latter river separates it from Missouri, and the former from Kentucky. It completely commands both streams, and in a military point of view may be properly considered as the key to what is usually denominated “the Great North-west.” The Illinois Central railroad connects it with Chicago, the greatest grain city of the world—with Lake Michigan, and the chain of lakes, and with the vast net work of railroads that branch from thence eastward. On the Missouri bank of the Mississippi river, two miles distant, is Ohio city, the initial point of the Cairo and Fulton railroad, designed to be extended to the Red river, in Arkansas, and thence to Galveston, in Texas. Twenty miles below, on the Kentucky side of the same giant river, is Columbus, which was soon after occupied and fortified by the rebel troops. As soon as General Lyon was vested with supreme command in Missouri, one of his first steps was to order a body of Federal troops to take possession of Cairo, under General Prentiss, who immediately proceeded thither, with 6,000 men, and commenced fortifying the place. On the 28th of May, Bird’s Point, on the Missouri side of the river, a commanding position, was also occupied, by direction of General Lyon, by the Fourth Missouri Volunteers, under the command of Colonel Schuttner.