In freezing winter weather, the Union forces under U.S. Grant had surrounded Fort Donelson and its 17,000 defenders two days before. On this day, significant reinforcements brought the besiegers' strength up to around 25,000 men. In the afternoon, naval units under Andrew Hull Foote attacked from the river but the impressive Confederate artillery defenses held and inflicted significant damage on the U.S. Navy gunboats, driving them off and wounding their commander aboard his flagship, the USS St. Louis. (By John Osborne)
David G. Martin, The Shiloh Campaign, March-April 1862 (Cambridge, MA: Da Capo Press, 2003), 31-32.