Humanities › History & Culture The Battle of Fort Donelson Share Flipboard Email Print John Parrot/Stocktrek Images / Getty Images History & Culture Military History Civil War Battles & Wars Key Figures Arms & Weapons Naval Battles & Warships Aerial Battles & Aircraft French Revolution Vietnam War World War I World War II American History African American History African History Ancient History and Culture Asian History European History Genealogy Inventions Latin American History Medieval & Renaissance History The 20th Century Women's History View More By Kennedy Hickman Military and Naval History Expert M.A., History, University of Delaware M.S., Information and Library Science, Drexel University B.A., History and Political Science, Pennsylvania State University Kennedy Hickman is a historian, museum director, and curator who specializes in military and naval history. He has appeared on The History Channel as a featured expert. our editorial process Facebook Facebook Kennedy Hickman Updated January 20, 2020 The Battle of Fort Donelson was an early battle in the American Civil War (1861-1865). Grant's operations against Fort Donelson lasted from February 11 to February 16, 1862. Pushing south into Tennessee with assistance from Flag Officer Andrew Foote's gunboats, Union troops under Brigadier General Ulysses S. Grant captured Fort Henry on February 6, 1862. This success opened the Tennessee River to Union shipping. Before moving upstream, Grant began shifting his command east to take Fort Donelson on the Cumberland River. The capture of the fort would be a key victory for the Union and would clear the way to Nashville. The day after the loss of Fort Henry, the Confederate commander in the West (General Albert Sidney Johnston) called a council of war to determine their next step. Strung out along a wide front in Kentucky and Tennessee, Johnston was confronted by Grant's 25,000 men at Fort Henry and Major General Don Carlos Buell's 45,000-man army at Louisville, KY. Realizing that his position in Kentucky was compromised, he began withdrawing to positions south of the Cumberland River. After discussions with General P.G.T. Beauregard, he reluctantly agreed that Fort Donelson should be reinforced and dispatched 12,000 men to the garrison. At the fort, the command was held by Brigadier General John B. Floyd. Formerly the U.S. Secretary of War, Floyd was wanted in the North for graft. Union Commanders Brigadier General Ulysses S. GrantFlag Officer Andrew H. Foote24,541 men Confederate Commanders Brigadier General John B. FloydBrigadier General Gideon PillowBrigadier General Simon B. Buckner16,171 men The Next Moves At Fort Henry, Grant held a council of war (his last of the Civil War) and resolved to attack Fort Donelson. Traveling over 12 miles of frozen roads, the Union troops moved out on February 12 but were delayed by a Confederate cavalry screen led by Colonel Nathan Bedford Forrest. As Grant marched overland, Foote shifted his four ironclads and three "timberclads" to Cumberland River. Arriving off Fort Donelson, U.S.S. Carondelet approached and tested the fort's defenses while Grant's troops moved into positions outside the fort. The Noose Tightens The next day, several small, probing attacks were launched to determine the strength of the Confederate works. That night, Floyd met with his senior commanders, Brigadier-Generals Gideon Pillow and Simon B. Buckner, to discuss their options. Believing the fort was untenable, they decided that Pillow should lead a breakout attempt the next day and began shifting troops. During this process, one of Pillow's aides was killed by a Union sharpshooter. Losing his nerve, Pillow postponed the attack. Irate at Pillow's decision, Floyd ordered the attack to commence. However, it was too late in the day to begin. While these events were occurring inside the fort, Grant was receiving reinforcement in his lines. With the arrival of troops led by Brigadier General Lew Wallace, Grant placed the division of Brigadier General John McClernand on the right, Brigadier General C.F. Smith on the left, and the new arrivals in the center. Around 3 p.m., Foote approached the fort with his fleet and opened fire. His attack was met with fierce resistance from Donelson's gunners and Foote's gunboats were forced to withdraw with heavy damage. The Confederates Attempt a Breakout The following morning, Grant departed before dawn to meet with Foote. Prior to leaving, he instructed his commanders not to initiate a general engagement but failed to designate a second-in-command. In the fort, Floyd had rescheduled the breakout attempt for that morning. Attacking McClernand's men on the Union right, Floyd's plan called for Pillow's men to open a gap while Buckner's division protected their rear. Surging out of their lines, the Confederate troops succeeded in driving back McClernand's men and turning their right flank. While not routed, McClernand's situation was desperate as his men were running low on ammunition. Finally reinforced by a brigade from Wallace's division, the Union right began to stabilize. However, confusion reigned as no one Union leader was in command on the field. By 12:30, the Confederate advance was stopped by a strong Union position astride Wynn's Ferry Road. Unable to break through, the Confederates withdrew back to a low ridge as they prepared to abandon the fort. Learning of the fighting, Grant raced back to Fort Donelson and arrived around 1 p.m. Grant Strikes Back Realizing that the Confederates were attempting to escape rather than seeking a battlefield victory, he immediately prepared to launch a counterattack. Though their escape route was open, Pillow ordered his men back to their trenches to re-supply before departing. As this was happening, Floyd lost his nerve. Believing that Smith was about to attack the Union left, he ordered his entire command back into the fort. Taking advantage of the Confederate indecisiveness, Grant ordered Smith to attack the left, while Wallace moved forward on the right. Storming forward, Smith's men succeeded in gaining a foothold in the Confederate lines while Wallace reclaimed much of the ground lost in the morning. The fighting ended at nightfall and Grant planned to resume the attack in the morning. That night, believing the situation hopeless, Floyd and Pillow turned command over to Buckner and departed the fort by water. They were followed by Forrest and 700 of his men, who waded through the shallows to avoid Union troops. On the morning of February 16, Buckner sent Grant a note requesting terms of surrender. Friends before the war, Buckner was hoping to receive generous terms. Grant famously replied: Sir: Yours of this date proposing Armistice, and appointment of Commissioners, to settle terms of Capitulation is just received. No terms except unconditional and immediate surrender can be accepted. I propose to move immediately upon your works. This curt response earned Grant the nickname "Unconditional Surrender" Grant. Though displeased by his friend's response, Buckner had no choice but to comply. Later that day, he surrendered the fort and its garrison became the first of three Confederate armies to be captured by Grant during the course of the war. The Aftermath The Battle of Fort Donelson cost Grant 507 killed, 1,976 wounded, and 208 captured/missing. Confederate losses were much higher due to the surrender and numbered 327 killed, 1,127 wounded, and 12,392 captured. The twin victories at Forts Henry and Donelson were the first major Union successes of the war and opened Tennessee to Union invasion. In the battle, Grant captured nearly one-third of Johnston's available forces (more men than all previous U.S. generals combined) and was rewarded with a promotion to major general.