April 27, 2011 began with a warning forecasters had almost never written: a major outbreak of intense, long-track, and perhaps violent tornadoes was expected — and by 1:00 AM, it had already begun. Over the next 24 hours, the most violent tornado day in modern American history unfolded across the Deep South: a morning squall line that spawned over 70 tornadoes before sunrise, then an afternoon of monster supercells feeding on off-the-charts instability and wind shear. In this video, we follow the day hour by hour — from Smithville, Mississippi, where the ground itself exploded, to Tuscaloosa, Hackleburg, and the EF5s that rewrote the record books. We break down the atmospheric setup that made it possible, the warnings that saved thousands, and why meteorologists still study this single day above all others. Every detail comes from NWS surveys, Storm Prediction Center archives, and survivor accounts.