The ocean is humanity's largest battlefield. Resting in its depths lie the lost ships of war, spanning the totality of human history. Many wrecks are nameless, others from more recent times are remembered, honored even, as are the battles that claimed them, like Actium, Trafalgar, Tsushima, Jutland, Pearl Harbor, and Midway. Underwater exploration is increasingly discovering long-lost warships from the deepest parts of the ocean, revealing a vast...