How did the Third Crown War end?
Here's what the lore says, drawn directly from the indexed sources:
-10600 DR * Third Crown War: Coronal Ynloeth dies in mysterious circumstances. Following this, Shantel Othreier is conquered by Aryvandaar ending the Third Crown War. Only the vassal realm of Ardeep holds out against the Vyshaan, though resistance movements spring up in Shantel Othreier and Miyeritar. * The Aelryth of Miyeritar believe Coronal Ynloeth's death to be a murder, and they launch a failed retaliatory strike against Tiru Orindraar.
Source: -10600 DR
-10900 DR * The Third Crown War begins when negotiations between Shantel Othreier and Aryvandaar break down and Aryvandaar attacks. * The Vyshaan lords of Aryvandaar gain a secret patron in Malkizid, a fallen solar.
Source: -10900 DR
-10700 DR * Third Crown War: The Battle of the Gods' Theater is fought, one of the greatest and bloodiest battles of the Crown Wars. Over 70,000 elves die as an orc horde falls upon the battling armies of Aryvandaar and Shantel Othreier. Aryvandaar is victorious and occupies the northern half of Shantel Othreier.
Source: -10700 DR
-11300 DR * Aryvandaar conquers Miyeritar, ending the First Crown War.
Source: -11300 DR