Summary
The Daynes figure among the Noble Houses of the Seven Kingdoms, sworn to protect House Nymeros Martell of Sunspear. House Dayne rules from the ancestral castle of Starfall which is situated in the western Red Mountains. This ruling seat is located on river Torrentine, along with the castles of Blackmont, and High Hermitage.Game of Throneslore says that House Dayne ruled as Kings of Torrentine from the days of the First Men but was subdued in Nymeria’s War.
King Vorian Dayne was the last Torrentine King and after his defeat, the Daynes became lord bannermen to House Nymeros Martell. The Daynes were powerful indeed with a greatsword, named Dawn of their own, which,unlike Tarly’s Heartsbaneor Mormont’s Longclaw, didn’t go to an heir but to a knight worthy of wielding it.

The Sword Of The Morning
The Great and the Noble Houses inGame of Thrones, all boast unique customs, traditions, and practices. House Dayne of Starfall, for example, does not pass down its ancestral greatsword, Dawn to heirs, but only to a knight in the House who is considered capable of carrying it. As such, the Sword of the Morning is the title bestowed upon this knight, and a few examples include Ser Davos Dayne, Ser Ulrick Dayne, and most notably, Ser Arthur Dayne who engaged in combat withNed Stark and his men inGame of Thrones.
The history of the Seven Kingdoms recognizes the Swords of the Morning, and in case, the Daynes do not find a knight worthy of Dawn, the title is dormant. While swords such as Ice, Longclaw, Dark Sister, and Blackfyre are forged from Valyrian steel, there is an interesting legend behind the forging of Dawn. The lore says that House Dayne’s founder tracked a falling star to the mouth of river Torrentine, where he found a magical stone. The castle of Starfall was built on this island and Dawn was forged from the metal of this fallen star. Dawn is described as pale in appearance, and the last known knight to wield it as perGame of ThroneswasRhaegar’s companion, Ser Arthur Dayne.

Ser Arthur Dayne Lore
Ser Arthur Dayne held the Sword of the Morning title, and he was a sworn brother in the prestige knightly order - the Kingsguard to the Mad King Aerys II Targaryen.Game of Thronesbriefly displays his name in season 4, episode 1 “Two Swords” in the Book of Brothers which lists all the deeds of knights who served in the Kingsguard. Ser Arthur Dayne’s entry says that he was Lord Beric Dayne’s second son andwielder of the greatsword, Dawn. Joffrey reads out loud Ser Arthur’s Dayne achievements, that he led the attack on the outlaw organization - the Kingswood Brotherhood, and defeated the infamous outlaw, the Smiling Knight in a single combat.
Fed of the Brotherhood’s attacks on the nobles, the Mad King dispatched a detachment of soldiers and eminent members of the Kingsguard to deal with them. The Kingswood Brotherhood’s base of operations was the Kingswood - a large forest acrossthe Blackwater Rushfrom the capital. Ser Arthur Dayne gained the trust of the smallfolk of Kingswood to his advantage and used the same to defeat this brotherhood of cutthroats, outlaws, and bandits.

Ser Arthur Dayne In Game Of Thrones
Ser Arthur Dayne was seen in HBO’sGame of Thronesseason 6, episode 3 “Oathbreaker,” when Bran and the Three-eyed Raven journeyed into the past and witnessed two of Aerys II Targaryen’s Kingsguard, the Sword of the Morning (Ser Arthur Dayne) and Ser Oswell Whent guarding the Tower of Joy. As Ned Stark and his few men, including Meera and Jojen Reed’s father, Howland Reed approach the tower, Bran notices Ser Arthur Dayne and says tothe Three-Eyed Raven:
Father said he [Dayne] was the best swordsman he ever saw.
The combat took place after Aerys' heir, Prince Rhaegar Targaryen was killed bythe Usurper, Robert Baratheonon the Trident. While Lyanna bled in the childbed, Ser Arthur Dayne and Ser Oswell Whent guarded the Tower. The two parties came face to face, and Ned said to the duo that he looked for them at the Trident. While Dayne refused to divulge any information about Lyanna Stark, he wished Ned Stark good fortune in the wars to come.
Bran noticed Ser Arthur Dayne was a far better swordsman than his father and was shocked to see that Ned didn’t beat Ser Arthur Dayne. Ned was disarmed, but Howland Reed who lay injured on the ground nearby, rose and thrust a dagger into the back of Dayne’s throat. Ned picked up Dayne’s greatsword, Dawn, and finished him off.
Game of Thrones' “Oathbreaker” reveals that the story that Bran heard a thousand times - about Ned Stark beating the legendary Sword of the Morning was a lie. Ned and Howland were the only two combatants left alive, whileSer Arthur Dayne, a true knight, died protecting his Prince’s wife, Lyanna Stark of Winterfell. After Robert’s coronation, Ned Stark returned the Dayne heirloom, Dawn to Starfall.