4x10: The Last Ship
Rollo and Ragnar will face each other in the context of a major battle between the French and the Vikings. The result will determine everyone's future
The Last Ship is the mid-season finale of Vikings season 4. The conflict between Vikings and Franks finally explodes, in what will come up to a battle of brothers. As we've seen, Rollo's in charge of a Frankish fleet that sails towards the Vikings. The battle begins giving the Norsemen a partial victory, so Rollo decides to send the rest of the ships.
Eventually, the Vikings retire and Ragnar jumps over Rollo. The Viking King will be captured and taken to Paris, giving Rollo a mention because of his effort.
Eight years passed, and Aslaug keeps reigning Kattegat. The long absence of the King produces a great resentment in his children and the rest of the town. When he finally arrives at the town, his sons pretend to take control of the crown, so he must face them in a deathmatch.