Arthur Dayne

Ser Arthur Dayne was a knight of House Dayne who bore the title of "Sword of the Morning" as he possessed the ancestral sword of House Dayne, Dawn. He was also a member of the Kingsguard under King Aerys II Targaryen.

Background
Ser Arthur was the second son of Beric Dayne, Lord of Starfall. As the wielder of the sword Dawn, which had been forged from the metal of a fallen star, he bore the title of "the Sword of the Morning". He was sent to deal with the Kingswood Brotherhood and subsequently killed the Smiling Knight in a duel.

Season 4
While skimming The Book of Brothers, King Joffrey Baratheon reads through the entry on Ser Arthur Dayne, mentioning his leading of the attack on the Kingswood Brotherhood and his defeat of the Smiling Knight, one of its members, in single combat. The Book of Brothers also mentions that at one point he was granted temporary command over the Kingsguard after Lord Commander Gerold Hightower suffered injuries. The entry concludes by recounting how he perished at the end of Robert's Rebellion alongside Ser Gerold at the Red Mountains of Dorne, fighting Lord Eddard Stark.

Season 6
Ser Arthur Dayne is seen with Ser Gerold Hightower, the Lord Commander of the Kingsguard under King Aerys II Targaryen, in a vision when Bran Stark sees into the past with the aid of the three-eyed raven. Near the end of Robert's Rebellion, Ser Arthur and Ser Gerold were stationed to guard the Tower of Joy by Prince Rhaegar Targaryen himself. When Lord Eddard Stark of Winterfell arrives with his bannermen, including Lord Howland Reed, in order to rescue the captive Lyanna Stark, Ser Arthur and Ser Gerold Hightower prevent the Northmen from entering the tower, peacefully. Ser Arthur is shown to be cordial to Eddard, but refuses to tell him why exactly the now-deceased Rhaegar wanted them to remain there or the whereabouts of Eddard's sister. Knowing there is no alternative, Ser Arthur and Ser Gerold fight the Northmen to hold the tower. Gerold is quickly killed by Lord Eddard in the melee, but Ser Arthur easily holds his own against the Northmen, cutting down most of them with his two swords, leaving just him and Eddard. As Bran watches them duel, he observes that Dayne is a better swordsman than his father. The three-eyed raven corrects him: "far better". Dayne eventually disarms Eddard but as he moves to strike him down, Howland Reed, who had been wounded earlier in the battle, sneaks up behind Dayne and stabs him in the back of the neck.

Ser Arthur is mortally wounded by the attack and falls to his knees, holding on to his sword for a few seconds before dropping it as his strength fades. The two look at each other as Eddard picks up Dawn, seeming ashamed of how he had survived. Although in agony, Arthur seems accepting of his fate; he had done his duty to the last. Eddard delivers the final blow, killing the legendary Sword of the Morning and sparing him from a slower, crueler death.

After killing Dayne, Eddard runs up into the tower where he finds Lyanna, dying after giving birth to Rhaegar's last living son, whom Eddard would pass off as his bastard son, Jon Snow.

Personality
"Father said he was the best swordsman he ever saw."

- Bran Stark cites his father's respect for Ser Arthur Dayne. Ser Arthur Dayne was a legendary knight and one of the finest men to have joined the Kingsguard, probably rivalled only by Ser Barristan Selmy. He was extremely courageous, leading the attack on the Kingswood Brotherhood and outmatching the Smiling Knight in sword combat - the Smiling Knight had previously defeated a young Jaime Lannister and was considered a terrifying opponent, making Arthur's defeat of him impressive. He is remembered as an excellent swordsman, and when he finally appears when Bran Stark wargs to the confrontation at the Tower of Joy, he is shown to be an incredibly skilled warrior, wielding two swords expertly and cleaving through nearly every opponent he faced - the Three-Eyed Raven pointed out that Arthur was vastly superior to Eddard Stark, and the only reason that he lost was because he was blindsided by Howland Reed.

Ser Arthur's reputation was such that, when people remembered him, it was in acclaim. Years later, Eddard Stark would comment that Ser Arthur Dayne was the best warrior Ned had ever encountered. Even when they outnumbered him, Ned and his companions were extremely wary about how to approach him, showing that Arthur's skill and reputation frightened them. In addition, Arthur was extremely loyal, to a fault, to Prince Rhaegar Targaryen, stating very matter-of-factly that the only reason he and Ser Gerold did not fight on the Trident was because Rhaegar ordered them to remain at the tower. Even after the deaths of Rhaegar and Aerys, he continued to follow Rhaegar's orders to protect the pregnant Lyanna Stark, even if that meant killing her brother Eddard. Although this probably had to do mostly with his vows, it could have also had something to do with the fact that Rhaegar's great-grandmother, Queen Dyanna, was born a Dayne, which could have in turn made Rhaegar and his children, including Jon, kin of some sort to Ser Arthur. Not much else is known about Ser Arthur, but he is shown to be extremely gentlemanly and polite in Bran's vision, greeting his father by title and even wishing him "good fortune in the wars to come"; a hint that despite his skills as a swordsman, even he sometimes, if not always, considered the possibility of losing before fighting someone else to the death. This also suggests that Arthur did not fear death as evidenced by the fact that he didn't beg for his life when Howland Reed wounded him. Instead, he simply faced Ned down before the latter finished him off.

Quotes
"I wish you good fortune in the wars to come."
 * Spoken by Arthur

- Arthur Dayne to Eddard Stark

"Ser Arthur Dayne, the Sword of the Morning... led the attack on the Kingswood Brotherhood. Defeated the Smiling Knight in single combat."
 * Spoken about Arthur

- King Joffrey Baratheon

Behind the scenes
In order to keep the Tower of Joy scene a secret during production, Luke Roberts was announced as playing Lord "Rowland Selwyn" instead of Arthur Dayne - apparently an amalgamation of the names of Howland Reed and Selwyn Tarth, Brienne's father.

In the books
In the A Song of Ice and Fire novels, Ser Arthur Dayne was a knight who had achieved legendary status by the time the events of the books take place. Dayne wielded the greatsword Dawn, a blade said to have been forged from metal from the heart of a fallen star, and bore the title of "the Sword of the Morning" (he is never stated to have wielded two swords, as portrayed in the TV series). He was a close friend of Prince Rhaegar Targaryen.

It was Arthur Dayne who knighted Jaime Lannister as a reward for his valor at the battle against the Kingswood Brotherhood. Dayne himself slew an infamous member of the Brotherhood, a fearsome swordsman known as the Smiling Knight, in single combat. During a spectacular duel, the Smiling Knight's sword broke in half, and Dayne backed off to allow his foe to take a new weapon. The Smiling Knight remarked that he really wanted Dayne's own sword, to which Dayne replied, "then you shall have it, Ser." When the fight resumed, Dayne killed him. Jaime would remember that when Ser Arthur Dayne fought with Dawn in hand, he was unstoppable, even though the Smiling Knight was an extraordinary foe. He considered Arthur, much like the rest of the Kingsguard of his youth, to be a good man.

Arthur Dayne is remembered as the greatest knight of his generation, not only in martial skill but in value and virtue as a true knight. Even Barristan Selmy, a living legend in his own right, thought that Ser Arthur surpassed himself in all respects. Ser Barristan, Jaime Lannister, and even Eddard Stark were all in awe of Ser Arthur, and recall him with nothing less than complete reverence. Jaime tells Loras Tyrell (a member of the Kingsguard in the books) that Dayne "could have slain all five of you with his left hand while he was taking a piss with the right". The fact that Arthur Dayne used to stand by and do nothing while the Mad King performed his atrocities did not taint his reputation at all.

When Rhaegar's apparent abduction of Lyanna Stark helped provoke Robert's Rebellion, he left Dayne and his fellow Kingsguard, Gerold Hightower and Oswell Whent, to guard Lyanna at the Tower of Joy in Dorne. After the Battle of the Trident, Eddard Stark and six companions arrived at the Tower to rescue her, and were confronted by the three Kingsguard, who refused to yield. Only Eddard and his friend Howland Reed survived the battle that followed - both Hightower, Whent and Dayne were climactically killed, but it is never explicitly stated how. Bran Stark recalled his father telling him that Dayne would have killed him if not for Howland Reed, hinting that Reed was heavily involved in Dayne's defeat. As a mark of respect, Eddard returned Dayne's famous sword to his relatives at Starfall.

When asked who would win in a duel, George R.R. Martin said that if Arthur Dayne and Barristan Selmy fought with equivalent weaponry it would be a very even fight - but if Dayne was armed with his sword Dawn, he would have the advantage over Selmy.

House Dayne is a Dornish House, but it is not incongruent that in the TV series he does not have the "Mediterranean" ethnic appearance of the Martells. When the Rhoynar people migrated to Dorne they settled primarily in the eastern river valleys, resulting in different subtypes of Dornishmen. The Martells are "Salty Dornishmen" from the eastern coasts, with large amounts of Rhoynar blood in their ancestry. In contrast, the Daynes are "Stony Dornishmen", whose holdings are in the Red Mountains along the western border of Dorne - and are known for having violet eyes despite not being of Valyrian descent. The Rhoynar barely settled in the more isolated mountains of the west, and thus Stony Dornishmen such as the Daynes are primarily the same First Men/Andal mix as the rest of Westeros.