"Four miles out to sea, three feet below the seabed, lay the Civil War submarine H.L. Hunley, lost without a trace on 17 February 1864 after sinking USS Housatonic. Discovered in 1995, a race began to protect this pioneering example of American technical ingenuity from potential looting and destruction. A Navy-led team of archaeologists and engineers developed a plan to excavate and raise the vessel under challenging conditions off the coast of South...