[3]) Grant's plan was to advance upon the fort on February 6 while it was being simultaneously attacked by Union gunboats commanded by Flag Officer Andrew Hull Foote.

A combination of accurate and effective naval gunfire, heavy rain, and the poor siting of the fort, nearly inundated by rising river waters, caused its commander, Brig.

On February 12, Grant's army proceeded overland 12 miles (19 km) to engage with Confederate troops in the Battle of Fort Donelson.

Gen. Gideon J. Pillow, acting on orders from Maj. Gen. Leonidas Polk, occupied Columbus, Kentucky, which overlooked strong defensive bluffs, to defend the Mississippi from Federal offensive action and was the terminus of the Memphis & Ohio railroad, which in turn leads southwards to the extremely important Charleston & Memphis railroad.

The riverside town was situated on 180 feet (55 m) high bluffs that commanded the river at that point, where the Confederates installed 140 large guns, underwater mines and a heavy chain that stretched a mile across the Mississippi River to Belmont, while occupying the town with 17,000 Confederate troops, thus cutting off northern commerce to the south and beyond.

Gen. Ulysses S. Grant, displaying the personal initiative that would characterize his later career, seized Paducah, Kentucky, a major transportation hub of rail and port facilities at the mouth of the Tennessee River.

If these rivers were opened to Union military traffic, two direct invasion paths would lead into western & eastern Tennessee, and the vital Memphis & SC Railroad and more.

John A. McClernand and Charles F. Smith, supported by the Western Gunboat Flotilla, commanded by United States Navy Flag Officer Andrew Hull Foote.

Insufficient transport ships this early in the war to deliver all of the army troops in a single operation required two trips upriver to reach the fort.

His subordinate Beauregard incessantly protested at his defensive strategy, urging him to advance and meet the unionist offensive, or at least reinforce the fortifications on the rivers.

Fort Henry was considered a liability due to its poor position & engineering which made it highly susceptible to being flooded during high tide and rain, and was garrisoned by a token force of 3,000-4,000 including the crews for the heavy guns, which was considered adequate for defending against enemy naval attack, in the meantime a new fort was being constructed on better ground upriver.

[citation needed] Fort Henry was a five-sided, open-bastioned earthen structure covering 10 acres (0.04 km2) on the eastern bank of the Tennessee River, near Kirkman's Old Landing.

Moving upriver, just inside the Tennessee border, Donelson selected the site of the fort on the Cumberland River that would bear his name.

Unlike its counterpart on the Cumberland, Fort Henry was situated on low, swampy ground and dominated by hills across the river.

Donelson's surveying team—Adna Anderson, a civil engineer, and Maj. William F. Foster from the 1st Tennessee Infantry—objected strongly to the site and appealed to Colonel Johnson, who inexplicably approved it.

[13] Seventeen guns were mounted in Fort Henry by the time of the battle, eleven covering the river and the other six positioned to defend against a land attack (18-pounder smoothbores).

McClernand's division was 3 miles (4.8 km) north of the fort, on the east bank of the Tennessee River, to prevent the garrison's escape.

They soon opened fire from a distance at 1,700 yards (around 1,554 meters), beginning an exchange of gunfire with Fort Henry that continued for over an hour.

Foote deployed the four ironclad gunboats in a line abreast, followed by the three timberclads, under the command of Seth Ledyard Phelps, which were held back for long-range, but less effective fire against the fort.

The high water level of the river and the low elevation of Fort Henry's guns allowed Foote's fleet to escape serious destruction.

The USS Essex was seriously damaged when a 32-pound shot from Fort Henry penetrated the ironclad, hitting the middle boiler and sending scalding steam through half the ship.

On February 7, the Union gunboats Cincinnati, St. Louis, and Essex returned to Cairo with whistles blowing and flying Fort Henry's captured Confederate flags upside down.

"[23] Fort Henry's fall quickly opened the Tennessee River to Union gunboats and shipping south of the Alabama border.

Immediately after the surrender, Foote sent Lieutenant Phelps with the three timberclads, Tyler, Conestoga, and Lexington, on a mission upriver to destroy installations and supplies of military value.

(The flotilla's ironclads had sustained damage in the bombardment of Fort Henry and were slower and less maneuverable for the mission at hand, which included pursuit of Confederate ships.)

The Union timberclads and their raiding parties destroyed supplies and an important bridge of the Memphis and Ohio Railroad, 25 miles (40 km) upriver.

[citation needed] After the fall of Fort Donelson to Grant's army on February 16, the Tennessee and Cumberland Rivers, two major water routes in the Confederate west, became Union waterways for movement of troops and material.

As Grant suspected, the Union capture of the two forts and the rivers flanked the Confederate forces at Columbus, and soon caused them to withdraw from that city and from western Kentucky.