It was the night the horse came inside the city (chapter 59), and Troy sang long at its first feast in ten years. The gates opened after the people fell asleep heavy with wine.
The fire was noticed first, and it jumped from roof to roof. People poured into the streets in their nightclothes.
It was a city that had held from its walls for ten years, but bringing it down took less than half a day. The story of that night was left by the losers, not the winners.