On her sixth birthday 80 years ago, Shizuko Nishio clung to her mother as U.S. B-29 bombers started a firestorm that turned humans to ash and Tokyo into a wasteland.

Five months before the United States dropped atomic weapons on Hiroshima and Nagasaki, the nighttime raid on March 9 and 10, 1945, was World War II's deadliest using conventional bombs.

At least 80,000 people died, with the figure likely more than 100,000, according to Japanese and U.S. historians.