The Field of Fire was the largest and most significant battle that transpired during Aegon’s Conquest of the Seven Kingdoms. After Aegon successfully conquered the first two kingdoms, the Kings of the Rock and the Reach formed an alliance to join their armies against Aegon’s invasion. King Loren Lannister joined his Kingdom of the Rock with King Mern Gardener’s Kingdom of the Reach and together they raised over 50,000 bannermen. Aegon’s army numbered less than 10,000 and they were losing the battle, until Aegon and his sisters unleashed all three of their dragons at once. It is said that this is the only time during the Conquest that all three dragons were ever unleashed together. Aegon and his dragons scorched the entire battlefield and this battle would henceforth be known as The Field of Fire. The dragons burned to death thousands of opposing soldiers, including King Gardener of the Reach and all his heirs.
The Field of Fire showed the rest of the Seven Kingdoms what Aegon and his dragons were capable of. In the aftermath of this battle, Loren Lannister bent the knee to Aegon and remained overlord of the Westernlands. After House Gardener had been wiped out in battle, their stewards, House Tyrell emerged and bent the knee to Aegon, becoming overlords of the Reach.