The Battle of Fort Donelson

The battle of Fort Donelson took place shortly after the battle of Fort Henry, Tennessee, February 6, 1862, in which Grant and Foote captured the fort and opened the Tennessee River for future Union movements. About 2,500 of the Confederate defenders at Fort Henry escaped before the surrender, marching the 12 miles (19 km) east to Fort Donelson.[1]
The Confederates now faced some difficult choices. Grant's army was now between Confederate Gen. Albert Sidney Johnston's two main forces (P.G.T. Beauregard at Columbus, Kentucky, with 12,000 men, and William J. Hardee at Bowling Green, Kentucky, with 22,000). Fort Henry was a deep salient in the center of the line defending Tennessee, and the railroad south of it had been cut, restricting the lateral mobility needed to rush reinforcements against the larger Union forces that faced them. Nearby Fort Donelson had only about 5,000 men. The Union might attack Columbus; they might attack Fort Donelson and thereby threaten Nashville, or Grant and Maj. Gen. Don Carlos Buell (in Louisville with 45,000 men) might attack Johnston head-on, Grant from behind, Buell from in front. Johnston was apprehensive about the ease in which Union gunboats defeated Fort Henry (not comprehending that the rising Tennessee River played a crucial role as it inundated the fort), but he was frankly more concerned about the threat from Buell than he was from Grant, suspecting the river operations might simply be a diversion.

Johnston decided on a course of action that forfeited the initiative across most of his defensive line, tacitly admitting that the Confederate defensive strategy for Tennessee was a sham. On February 7, at a council of war held in the Covington Hotel in Bowling Green, he decided to abandon Western Kentucky by withdrawing Beauregard from Columbus and to evacuate Bowling Green and move his forces south of the Cumberland River at Nashville. Despite his misgivings about its defensibility, he agreed to advice from Beauregard that he should reinforce Donelson with another 12,000 men, knowing that a defeat there would mean the inevitable loss of Middle Tennessee and the vital manufacturing and arsenal city of Nashville.
Johnston wanted to give command of Fort Donelson to Beauregard, who had performed ably at Bull Run, but the latter declined because of a throat ailment. Instead, the responsibility went to Brig. Gen. John B. Floyd, who had just arrived following an unsuccessful assignment under Robert E. Lee in western Virginia. Floyd was a wanted man in the North for graft and secessionist activities as Secretary of War under the administration of President James Buchanan. His background was political, not military, but he was the senior brigadier general on the Cumberland.

Battle of Fort Henry and the movements to Fort Donelson. Confederate Union
On the Union side, Maj. Gen. Henry W. Halleck, Grant's superior as commander of the Department of the Missouri, was also apprehensive. He had authorized Grant to capture Fort Henry, but now he felt that continuing to Donelson was a risky enterprise. And despite Grant's success so far, Halleck had little confidence in his subordinate, considering him reckless. He attempted to convince his own rival, Don Carlos Buell, to take charge of the campaign as a means of getting his additional forces engaged, but despite Johnston's high regard for Buell, he was as passive as Grant was aggressive. Grant never suspected that his superiors were considering relieving him, but he was well aware throughout the campaign that any delay or reversal might be an opportunity for Halleck to lose his nerve and cancel the operation.
On February 6, Grant had wired to Halleck, "Fort Henry is ours. ... I shall take and destroy Fort Donelson on the 8th and return to Fort Henry." This self-imposed deadline was overly optimistic because of three factors: miserable road conditions on the 12-mile march to Donelson; the need to use troops to carry supplies away from the rising flood waters. Damage that had been sustained by Foote's Western Flotilla during the artillery duel at Henry. If he had been able to move that quickly, Grant might have taken Fort Donelson on that day. Early in the morning of February 11, Grant held a council of war in which all of his generals supported his plans for an attack on Donelson, with the exception of McClernand, who had some reservations. This was the last time that Grant held such a council during the Civil War. The Union army was again victorious at this battle.