Forts Henry and Donelson: The first important operation in 1862 took place in the Western Theater, where Federal forces were divided into two commands: one under Brig. Gen. Carlos Buell at Louisville, the other under Maj. Gen. Henry W. Halleck at St. Louis. Facing Buell and Halleck was Gen. Albert Sidney Johnston with 43,000 Confederate troops, occupying a line of forts and camps that extended from Cumberland Gap in Virginia, through Bowling Green, Ky., to New Madrid and Island No. 10 on the Mississippi. To protect a lateral railroad, vital to their communications, the Confederates has built Fort Henry on the Tennessee River and Fort Donelson on the on the Cumberland. The two forts were on the northern border of Tennessee and only 10 miles apart.
In February 1862 Halleck effected a strategic penetration of the center of Johnston's line by the Henry and Donelson Campaign (6-16 February 1862). Federal troops under Brig. Gen. Ulysses S. Grant moved on boats up the Tennessee River to a point near Fort Henry, landed, and marched overland to seize the fort. Brig. Gen. Lloyd Tilghman sent most of his garrison to Fort Donelson, and on 6 February surrendered to Flag Officer Andrew H. Foote, whose river flotilla had subjected the fort to a gunboat bombardment. Grant at once turned against Fort Donelson, which he invested on 12 February with a reinforced command of more than 25,000 men. Meanwhile the fall of Fort Henry had rendered the Confederate position at Bowling Green untenable, Johnston had therefore sent 12,000 men to reinforce Fort Donelson, and retired toward Nashville with about 14,000 men.
Fort Donelson was a strong position, and gunboats attempting a bombardment were roughly handled. Grant prepared to lay siege, but when a Confederate sortie failed he made an attack. This resulted in the surrender of the fort and 11,500 Confederate troops by Brig. Gen. Simon B. Buckner on 16 February 1862. A number of Confederate units were able to escape shortly before the capitulation. Union losses at Donelson were 500 kited, 2,108 wounded, and 224 missing. Confederate losses, aside from prisoners were about 2,000 killed and wounded.