Showdown at the Tower of Joy

The Showdown at the Red Mountains was the last engagement of Robert's Rebellion, a civil war that divided the Seven Kingdoms and led to the fall of the Targaryen dynasty and the rise of the Baratheon dynasty.

Prelude
Following the Sack of King's Landing and the death of the Mad King, some loyalist forces still remained on the field, unaware of the fall of the capital and that Robert Baratheon had taken the Iron Throne. Despite their falling out over the murder of the royal family at the hands of House Lannister, Ned Stark was sent south to put an end to the Siege of Storm's End

After Lord Mace Tyrell bent the knee and his siege of Storm's End lifted, a small group loyal to the Mad King still remained: the Kingsguard who had not been either at the Battle of the Trident or at the fall of the capital. When the rebellion had grown into a massive force that threatened the Iron Throne, Ser Gerold Hightower, Lord Commander of the Kingsguard, was dispatched by King Aerys to have Prince Rhaegar Targaryen return to the capital. Prince Rhaegar returned and would die in the Battle of the Trident, while Ser Gerold remained.

Events
At the Red Mountains of Dorne, Ned Stark and a small group of bannermen fought Ser Gerold along with his two remaining sworn brothers: Ser Arthur Dayne, the Sword of the Morning, and Ser Oswell Whent. There were only two survivors of the fight: Howland Reed and Ned Stark, whose life had been saved by the crannogman.

Aftermath
Having dealt with the last Targaryen loyalists, Ned Stark returned home to Winterfell, along with the body of his sister, Lyanna Stark, who had recently perished. While his friendship with Robert was mended over their mutual love for Lyanna, who had been Robert's betrothed, both men would remain haunted by her death.

In the books
In the A Song of Ice and Fire novels, Ned Stark had been accompanied by six men to the Tower of Joy, in the Red Mountains, to recover Lyanna Stark. The six men were:
 * Howland Reed
 * Willam Dustin, Barbrey Dustin and the head of House Dustin
 * Ethan Glover, former squire to the late Brandon Stark
 * Martyn Cassel, father of Jory Cassel and brother of Rodrik Cassel
 * Theo Wull, of Clan Wull
 * Ser Mark Ryswell

When Ned Stark is injured fighting Jaime Lannister, he dreams about the events that took place in the Tower:

"::: “I looked for you on the Trident,” Ned said to them.
 * “We were not there,” Ser Gerold answered.
 * “Woe to the Usurper if we had been,” said Ser Oswell.
 * “When King's Landing fell, Ser Jaime slew your king with a golden sword, and I wondered where you were.”
 * “Far away,” Ser Gerold said, “or Aerys would yet sit the Iron Throne, and our false brother would burn in seven hells.”
 * “I came down on Storm's End to lift the siege,” Ned told them, and the Lords Tyrell and Redwyne dipped their banners, and all their knights bent the knee to pledge us fealty. I was certain you would be among them.”
 * “Our knees do not bend easily,” said Ser Arthur Dayne.
 * “Ser Willem Darry is fled to Dragonstone, with your Queen and Prince Viserys. I thought you might have sailed with him.”
 * “Ser Willem is a good man and true,” said Ser Oswell.
 * “But not of the Kingsguard,” Ser Gerold pointed out. “The Kingsguard does not flee.”
 * “Then or now,” said Ser Arthur. He donned his helm.
 * “We swore a vow,” explained old Ser Gerold.
 * Ned's wraiths moved up beside him, with shadow swords in hand. They were seven against three.
 * “And now it begins,” said Ser Arthur Dayne, the Sword of the Morning. He unsheathed Dawn and held it with both hands. The blade was pale as milkglass, alive with light.
 * ''“No,” Ned said with sadness in his voice. “Now it ends.”"