Answer
Akechi Mitsuhide, Nobunaga's trusted general, betrayed him at the Honnō-ji Incident in 1582. Mitsuhide's motives remain unclear, but theories include personal ambition, resentment towards Nobunaga's harsh rule, or a desire to protect the Ashikaga shogunate. Nobunaga's death plunged Japan into chaos, leading to a period of civil war known as the Sengoku period.