When Robb Stark led the host of the north south to war, he faced two Lannister armies at once: Lord Tywin's great host coming up the kingsroad, and Ser Jaime's army investing Riverrun. At the Twins the young wolf divided his strength. He sent the greater part of his foot down the kingsroad under Roose Bolton of the Dreadfort to fix Lord Tywin in place, while he himself crossed the Green Fork with all his horse and swung west toward Riverrun, screened by the outriders of his great-uncle Ser Brynden Tully, the Blackfish. So well was the movement veiled that Ser Jaime, secure in his siege lines and contemptuous of the boy he faced, never learned that a mounted host of many thousands was closing upon him in the dark.
The trap was sprung in the Whispering Wood, a wooded vale hard by Riverrun, on a night without a moon. Caught with only a raiding party of his knights among the trees, Jaime found himself surrounded by Stark riders pouring down out of the darkness on every side. The fighting was short, savage, and confused, the sort of close butchery in which mounted lances count for little. Jaime Lannister fought his way toward the Stark banners in a bid to end the battle by killing Robb himself, and cut down a dozen men to reach him, among them the young Daryn Hornwood and the two Karstark sons, Torrhen and Eddard, whose deaths their father Lord Rickard would never forgive nor forget. But the Kingslayer could not reach the wolf, and at the last he was pulled from his horse and taken alive.
The Whispering Wood was among the most complete victories of the war. Jaime's cavalry was destroyed or scattered, and the finest knight of the Seven Kingdoms was made a prisoner of a boy of fifteen. With the Kingslayer in chains and his army in ruins, the way to Riverrun lay open, and within days Robb would fall upon the leaderless Lannister siege camps and break them utterly. The tidings of the disaster, coming so soon after Lord Tywin's own indecisive fight upon the Green Fork, shook the confidence of the Lannister cause throughout the riverlands.