(Newser) – For more than 150 years, researchers have scratched their heads over a Civil War mystery—and now a Navy engineer says she's solved it. Rachel Lance has been diving deep into the 1864 sinking of the Confederate submarine HL Hunley, which mysteriously went down shortly after sinking the Union's USS Housatonic sloop with a torpedo, reports a Hakai Magazine article posted at Smithsonian.com. Over three years, Lance—a Duke grad student with no experience in forensics, no help from experts who'd long been on the case, and no access to the excavated sub itself—carried out what Gizmodo calls an "exhaustive … analysis" and finally arrived at a conclusion published in PLOS ONE: that the torpedo created blast waves that pierced the Hunley's hull and instantly killed the eight crew, whose skeletons were found intact during the sub's excavation near Charleston, SC, in 2000.

Lance looked at other theories swirling around the Hunley's fate, including low oxygen or a bullet fired by the Housatonic that punctured the sub. She became obsessed, to the point she'd zone out during meals. "There was something viscerally terrifying about the fact that eight people died that night, and we had no idea how or why," she tells Hakai. Her injury biomechanics background finally led her to her shock wave theory. "When blast waves hit an air space, they slow down like a car hitting a wall," she says. "Except in this case, the wall is the surface of the lungs." A mini replica of the Hunley she dubbed the CSS Tiny and a series of test explosions in a rural pond helped her prove her theory, per CNN. Other researchers remain unconvinced, but Hakai says now Lance's theory is "their theory to disprove." More on her project here. (The Hunley looks a lot better these days.)

