Answer
The Honnō-ji Incident was a key event that led to the rise of Toyotomi Hideyoshi as the supreme ruler of Japan. The incident occurred on June 21, 1582, when Akechi Mitsuhide, a former ally of Hideyoshi, attacked and killed the warlord Oda Nobunaga at his headquarters in Honnō-ji. Mitsuhide had been conspiring with other daimyōs to overthrow Nobunaga, who had become increasingly unpopular due to his harsh rule.