In April 1861, Lincoln declared a blockade on Southern ports. It was only a matter of time before the Union navy would pay a visit to the bustling Confederate harbor in Mobile Bay. Engineers built elaborate obstructions and batteries, and three rows of torpedoes were laid from Fort Morgan to Fort Gaines. Then, in August 1864, the inevitable came. A navy fleet of fourteen wooden ships lashed two by two and four iron monitors entered the lower bay, with the USS Tecumseh in the lead. A torpedo, poised to strike for two years, found the Tecumseh and sank it in minutes, taking ninety—three crewmen with it. Join author David Smithweck on an exploration of the ironclad that still lies upside down at the bottom of Mobile Bay.