Battle of the Golden Tooth

When Jaime Lannister flees King's Landing after his clash with Eddard Stark over Tyrion's arrest, he heads for Casterly Rock and starts raising an army. Edmure Tully, ruling Riverrun while his father lies bedridden, sends word demanding answers from Lord Tywin. None come, so Edmure orders Lord Vance and Lord Piper to hold the pass beneath the Golden Tooth — not a foot of ground given up if the Lannisters advance.

To weaken Riverrun before the clash, Tywin turns Ser Gregor Clegane loose on the Riverlands. Flying no banner and giving no warning, the Mountain burns villages as he goes. Edmure sends Marq Piper and Karyl Vance, camped with their fathers at the Golden Tooth, to look for survivors; Raymun Darry rides for his own lands but arrives too late — Clegane has already crossed the Red Fork and reached safety on Lannister ground.

On old Lord Hoster's advice, the three knights bring the victims to King's Landing to ask the king's leave before striking back. Meanwhile Edmure scatters armed men through every village within a day's ride of the Lannister border, splitting his own strength just when he needs it whole.

Jaime Lannister's army falls on the pass's defenders before they see it coming and routs them. Lord Vance dies in the fighting; Lord Piper falls back toward Riverrun with what's left of his men, the Kingslayer at his heels. The blow opens the Lannister campaign in the Riverlands.

Jaime doesn't stop there: he chases the survivors to the walls of Riverrun and beats the river lords again. Edmure Tully is wounded and taken prisoner along with many of his knights. Lord Blackwood gets what's left of the force behind the walls, and Riverrun is put under siege at once.

With the river lords beaten at the Golden Tooth, the road into the Riverlands stands open. Jaime Lannister and his army push on unopposed until they reach Riverrun, and the war that began in that pass now sits at the Tullys' gates.