Ser Arthur Dayne proved himself worthy to wield the Dayne family's ancestral sword, Dawn, and thus became his generation's Sword of the Morning. Dawn was a pale, shimmering sword said to have been forged from the heart of a fallen star, and whose material mimicked many of the qualities of Valyrian steel.
Ser Arthur distinguished himself as a member of Aerys II Targaryen's Kingsguard and became famous in Westeros as perhaps the greatest swordsman in the land. His notable exploits include the campaign he led against the outlaw gang called the Kingswood Brotherhood, which culminated in him killing the Smiling Knight in single combat. After the battle, he knighted a young Jaime Lannister for his bravery during the campaign.
He accompanied Prince Rhaegar Targaryen to Dorne during the last days of Robert's Rebellion, and stood guard over Lyanna Stark at the Tower of Joy. He was ultimately defeated and slain there by Eddard Stark and Howland Reed. Eddard journeyed to Starfall, the Dayne ancestral home, and returned Dawn to Arthur's sister Ashara as a mark of respect.