Spoilers for this episode.
Ragnar's sons take their army into Wessex, where Ivar argues for a different approach to battle. Bjorn listens despite their struggle over command. Instead of allowing Aethelwulf to meet the force on his own terms, the Vikings repeatedly draw the Saxons onward and disrupt their movements. Ivar predicts how their opponent will react, and Bjorn puts that judgement to use as the armies close on one another.
Ecbert sends Aethelwulf to war while telling Judith to return to her husband. Before leaving, Aethelwulf speaks warmly to Alfred, treating him as his son despite the circumstances of his birth. Harald's grievance against Ellisif also turns violent. He kills her husband, then accepts her apparent change of heart. Halfdan intervenes when she tries to kill Harald, killing Ellisif to protect his brother.
Back in Kattegat, Egil attacks while the great army is abroad. Lagertha's preparations give her defenders a chance to withstand the assault, and Torvi and Astrid help fight off the invaders. Egil is captured and tortured, revealing that Harald financed the attack. Lagertha holds the settlement, though the fighting leaves casualties around her. In Wessex, the brothers' manoeuvres bring Aethelwulf into the battle they have prepared. The episode leaves that confrontation underway, with Ecbert's court still waiting for the outcome of his son's campaign.