 After a two-hour artillery duel, largest ever on the North American continent, 15,000 Confederates leave the wood line on Seminary Ridge, move a mile to the Union position, and it was devastating. Lee lost 5,000 soldiers in just an hour as 200 canyons destroyed these troops that were self-canalizing, actually, on the battlefield. So Lee limps off. It's a disaster for the Confederates.