Robb Stark calls the northern bannermen to war and marches south with twenty thousand men to rescue his father. At the Twins, a strategic river crossing held by the shrewd Lord Walder Frey, Catelyn negotiates passage by promising that Robb will marry one of Frey's daughters and that Arya will marry one of Frey's sons. Robb splits his forces, sending a feint toward Tywin Lannister's main army while he leads the bulk of his men to Riverrun. The feint engages Tywin's forces in the Battle of the Green Fork, where Tyrion fights alongside the hill tribes and is knocked unconscious early in the fighting. Tywin wins the battle but realizes too late that the main Stark army was not there. Robb's true force ambushes Jaime Lannister's army besieging Riverrun at the Battle of the Whispering Wood. The Starks win decisively, and Robb personally captures Jaime Lannister. Catelyn confronts the captive Jaime, who taunts her but cannot deny his vulnerability. In King's Landing, Varys visits Ned in the dungeon and urges him to confess to treason and declare Joffrey the rightful king, arguing that Sansa's life depends on it. Ned, a man who has refused every compromise, agrees to lie for his daughter's sake. At the Great Sept of Baelor, Ned is brought before the crowd and publicly confesses that he conspired against the rightful king. Cersei and the Small Council expect Joffrey to show mercy and send Ned to the Wall. Instead, Joffrey, relishing his power, orders Ned's execution. Cersei and the councilors visibly react with alarm, but Joffrey will not be overruled. Ser Ilyn Payne beheads Ned Stark with his own sword, Ice, as Sansa screams and Arya, hidden in the crowd, is grabbed by Yoren of the Night's Watch, who shields her eyes and pulls her away. Across the sea, Drogo's wound festers into a deadly infection. Daenerys desperately asks Mirri Maz Duur to use blood magic to save him. Mirri agrees but warns that only death pays for life. During the ritual, Daenerys goes into premature labor and is carried into the tent where the dark magic is being performed.