In 299 AC Robb Stark carried the war into the heart of the westerlands, the first foe to bring fire and sword to Lannister lands in living memory. To meet him Ser Stafford Lannister, uncle and good-father to Lord Tywin, had gathered a great but green host of fresh levies near Lannisport and marched east to bar the young wolf's path, making camp at a place called Oxcross in the hills beyond the Golden Tooth. Stafford's men were raw and ill-drilled, and he kept his camp carelessly, setting few sentries and reckoning the northern army still far off.
Guided through the high country by the mountain clansmen and screened by the dark, Robb fell upon the sleeping camp before dawn. His direwolf Grey Wind is said to have torn through the horse lines ahead of the attack, so that the westermen woke to find their mounts maddened and scattered and the enemy already among their tents. The green host never formed its lines. It was less a battle than a slaughter; the levies broke and were ridden down, and Ser Stafford Lannister himself was slain. With Stafford dead and his army destroyed, the westerlands lay open, and Robb loosed his riders to harry and burn Lord Tywin's own country, taking castles, cattle, and gold and drawing the war ever deeper toward Casterly Rock.