Ichthys Battles Dreadthorn
What happened
Neither dragon could win, and the cost in lives was catastrophic.
Notes
Ichthys, the white arch-dragon, rallied the people and their allies against Dreadthorn's forces. The war lasts 3 years with catastrophic results. Neither dragon defeats the other.
The timeline sheet calls Ichthys "the great lion"; every other source calls him the white arch-dragon.