Tennessee joined the Southern Confederacy, but Kentucky resisted all the coaxing, threatening, and planning of the leaders of the Rebellion. Some Kentuckians talked of remaining neutral, of taking no part in the great contest; but that was not possible. The Rebels invaded the State, by sailing up the Mississippi and taking possession of Columbus,--a town twenty miles below the mouth of the Ohio. They also advanced from Nashville to Bowling Green. Then the State decided for the Union,--to stand by the old flag till the Rebellion should be crushed. The Rebels erected two forts on the northern line of Tennessee. Looking at your map, you see that the Cumberland and Tennessee Rivers are near together where they enter the State of Kentucky. They are not more than twelve miles apart. The fort on the Tennessee River was named Fort Henry, the one on the Cumberland, Fort Donelson. A good road was cut through the woods between them, so that troops and supplies could be readily removed from one to the other. Fort Henry was on the eastern bank of the Tennessee, and Fort Donelson on the western bank of the Cumberland. They were very important places to the Rebels, for at high water in the winter the rivers are navigable for the largest steamboats,--the Cumberland to Nashville and the Tennessee to Florence, in Northern Alabama,--and it would be very easy to transport an army from the Ohio River to the very heart of the Southern Confederacy. The forts were built to prevent any such movement of the Union troops. [Illustration: THE FORTS.] The bluffs of the Mississippi River at Columbus are two hundred feet high. There the Rebels erected strong batteries, planting heavy guns, with which they could sweep the Mississippi far up stream, and pour plunging shots with unobstructed aim upon any descending gunboat. They called it a Gibraltar, because of its strength. They said it could not be taken, and that the Mississippi was closed to navigation till the independence of the Southern Confederacy was acknowledged. Early in the war it was seen that a fleet of gunboats would be needed on the Western rivers, and Captain Andrew H. Foote of the navy was placed in charge of their construction. They were built at Cincinnati and St. Louis, and taken to Cairo, where they received their armament, crews, and outfit. You have heard of Cairo. I do not mean the ancient city on the banks of the Nile, but the modern town on the tongue of land at the mouth of the Ohio. Charles Dickens has given a description of the place in one of his delightful books,--Martin Chuzzlewit. It was a forest, with a few log-huts, when Mark Tapley resided there, and all the people were smitten with fever and ague. It is a town now, with several thousand inhabitants. In the spring the town is sometimes overflowed, and the people navigate the streets with boats and rafts. Pigs look out of the chamber windows, and dogs, cats, and chickens live on the roofs of houses at such times.