army during a winter offensive to control of the Mississippi River. Grant believed that such control would enable him to divide the Confederacy in two. (see Battle of Fort Donelson) On August 25, 1863, a Confederate force attacked the fort and demanded surrender by Union troops. Their attack was unsuccessful and was repulsed by the Union garrison. Union attack Fort Donelson was attacked by General U.S Grant and Flag Officer Andrew Foote, who surrounded the fort and captured it after a short siege. On February 6, Grant was ordered by General Henry Halleck to assault Fort Donelson immediately and capture it by February 8. Grant made reconnaissance, observed the natural obstacles and Confederate improvements, and knew the fort would not be taken by the 8th. He organized and had Brigadier Generals John A. McClernand, Charles F. Smith, and Lew Wallace prepare for a land assault while Flag Officer Foote moved his gunboats to assault from the river. After minor skirmishes with Confederate cavalry en route, the assault on Fort Donelson began on February 12. On February 14, a naval battle took place, in which Union ships suffered serious damage. After attempting in vain to escape their tenuous position on February 15 via roads to Nashville, the Confederates capitulated, surrendering Fort Donelson to the Union on February 16. Fort Donelson under Union control The Union was ecstatic when the news of Fort Donelson's surrender reached the capital and cities. Union forces now controlled one of the largest forts in the western theater. The war had been going badly for the Union in Virginia, but the captures of Fort Henry and Fort Donelson were promising victories. After the front line shifted away from Fort Donelson, it became of little strategic importance, but continued to hold a garrison of Union troops. Later, the fort was attacked by a Confederate force of 450 infantrymen, 335 cavalrymen, and two field guns. The Union garrison consisted of four companies (404 men) of the 71st Ohio Regiment. After suffering 30 casualties, the Confederates retreated. They were pursued by the Fifth Iowa Cavalry, but to no avail. Union commanders Ulysses S. Grant (Feb 1862) Abner Harding (Sept 1862–1863) William W. Lowe (Feb 1863) After the war The Fort Donelson National Battlefield was created in 1928, and the park was listed on the National Register of Historic Places on October 15, 1966. It was redesignated as a national battlefield