500
What was the conflict which united the Seven Kingdoms (250 extra points if you can name the houses it destroyed/replaced)?
The War of Conquest (The Gardeners, Hoares, and Durrandons were slain and replaced by the Tyrells, Greyjoys, and Baratheons and Aegon raised up the Tullys to rule over the Riverlands, which had been under ironborn occupation prior to his arrival).