Brigadier General Grant marched his troops from the site of his recent victory at Fort Henry across land from the Tennessee River to the much more daunting Confederate strongpoint at Fort Donelson, on the banks of the Cumberland in Stewart County, Tennessee. In freezing winter weather, the Union forces surrounded the fort and its 17,000 defenders and began probing its defenses. Meanwhile, a small attack by U.S. Navy gunboats tested the Confederate riverside gun emplacements. (By John Osborne)
David G. Martin, The Shiloh Campaign, March-April 1862 (Cambridge, MA: Da Capo Press, 2003), 30-31.