The Field of Fire is a legendary battle from when Aegon Targaryen was conquering the Seven Kingdoms. His motley army, mostly conscripts from his conquests, faced the larger host of King Loren and King Mern in the Reach. All three Targaryen dragons--Balerion, Vhaghar and Meraxes--were unleashed, and the host was decimated. King Loren survived and swore fealty to Aegon.