Major-General Polk, commanding at Columbus, having received instructions from the Confederate War Department, through General Beauregard, to evacuate Columbus and select a defensive position below, adopted that embracing Madrid Bend on the Tennessee shore, New Madrid on the Missouri shore, and Island No. Ten between them. The bluffs on the Missouri shore terminate abruptly at Commerce. Thence to Helena, Arkansas, the west bank of the Mississippi is everywhere low and flat, and in many places on the river, and to much greater extent a few miles back from the river, is a swamp. From Columbus to Fort Pillow, the Tennessee shore is of the same character. The river flowing almost due south for some miles to Madrid Bend, curves there to the west of north to New Madrid, and there making another bend, sweeps to the southeast and then nearly east, till, reaching Tiptonville, a point nearly due south of Madrid Bend, it turns again to the south. Island No. Ten begins at Madrid Bend and looks up the straight stretch of the river. From Island No. Eight, about four miles above Island No. Ten, the distance across the land to New Madrid is six miles, while by river it is fifteen. The distance overland from Island No. Ten to Tiptonville is five miles, while by water it is twenty-seven. Commencing at Hickman, between Madrid Bend and Columbus, a great swamp, which for a part of its extent is a sheet of water called Reelfoot Lake, extends along the left bank of the Mississippi, and discharges its waters into the Mississippi forty miles below Tiptonville, leaving between it and the river the peninsula which lies immediately below Island No. Ten, and opposite New Madrid. Immediately below Tiptonville the swamp for many miles extends entirely to the river. The peninsula is, therefore, substantially an island, having the Mississippi on three sides, and Reelfoot Lake, with its enveloping swamp, on the other. A good road led from the Tennessee shore, opposite Island No. Ten, along the west border of the swamp and the lake to Tiptonville. The only means of supply, therefore, for the forces on Island No. Ten and this peninsula, were by the river. If the river were blockaded at New Madrid, supplies must be landed at Tiptonville and conveyed across the neck of the peninsula by the road. From this peninsula there was no communication with the interior except by a small flatboat which plied across Reelfoot Lake, more than a mile across, by a channel cut through the cypress-trees which cover the lake. Supplies and reinforcements could not, therefore, be brought to any considerable extent by the land side; nor could escape, except by small parties, be made in that direction. A mile below Tiptonville begin the great swamps on both sides of the Mississippi. If batteries could be planted on the lowest dry ground, opposite and below Tiptonville, so as to command the river and effectually intercept navigation, the garrison of Island No.