Capture of Riverrun

The Taking of Riverrun is a battle during the War of the Five Kings. It is mentioned in the episode "The Door", and sees the retaking of the castle Riverrun by House Tully from the armies of House Frey.

Prelude
After the Red Wedding, House Frey are elevated to the Great House of the Riverlands as Lords Paramount of the Trident and Lords of Riverrun. However, Ser Brynden Tully, known as the Blackfish, eventually escapes the Red Wedding. Though initially unconcerned, Lord Walder Frey later orders a manhunt for the hero of the War of the Ninepenny Kings, without result, however.

Events
The Blackfish eventually reforms the remaining loyal garrisons, attacks and retakes Riverrun from the armies of House Frey. Lothar Frey and Walder Rivers eventually survive and return to the Twins.

Aftermath
Following the Blackfish's reconquest of Riverrun, several river lords, such as Houses Mallister and Blackwood rising in rebellion. This, combined with the incessantly harassment from the Brotherhood without Banners, who are also rising the smallfolk in rebellion, weakens the Frey's hold on the Riverlands to the point they don't have the force to take back the castle. However, King Tommen Baratheon eventually relieves Ser Jaime Lannister of his Kingsguard duties and sends him to deal with the Blackfish and retake the castle for the Freys. This sets stage for another open conflict between the Tullys and the Lannisters.

In the books
In the A Song of Ice and Fire novels, Brynden Tully does not lose Riverrun after the Red Wedding and continues holding the castle in defiance of the Freys and the Iron Throne. In fact, Riverrun is besieged by House Lannister and Frey, in an effort to remove the final vestiges of resistance in the riverlands and install Ser Emmon Frey as the new Lord of Riverrun, as the terms of the alliance between the Freys and Lannisters dictate.

Brynden Tully eventually anticipates the siege. He gathers all the foodstuffs and goods he can within the castle, expels all the unnecessary mouths, and prepares for a long siege. Ryman commands a large and disorderly Frey encampment north of the Tumblestone. South of the Red Fork are Lord Emmon, Ser Forley Prester with other westermen, and rivermen who knelt to the Iron Throne after the Red Wedding. Daven commands House Lannister's camp between the Tumblestone and the Red Fork. To prevent Riverrun's defenders from escaping, Ser Manfryd Yew and Ser Raynard Ruttiger command a boom across the Red Fork east of the castle.

Later, Ser Jaime Lannister leaves King's Landing with near one thousand reinforcements, but while traveling to Riverrun he leaves the Holy Hundred at Harrenhal and sends Ser Ronnet Connington with some of the Mountain's men to Maidenpool. Jaime treats with Brynden Tully in attempt to get him to surrender, but the Blackfish stubbornly refuses. He points out he outnumbers Brynden, but the Blackfish points out that twenty times the men requires twenty times the food—a difficult situation, given the supply shortages and lack of Frey cooperation in regards to food shipments.

However, the siege eventually ends when Jaime sends Edmure Tully, Frey's prisoner following the Red Wedding, to talk with his uncle. Edmure eventually surrenders the castle, but not before letting Brynden escape.