The Danish King Sweyn orders his armies’ English advances halted to give them time to rest for the winter. That means Askeladd’s crew’s contract work with the army ceases, which means they have to do as the birds do: migrate south in search of food.
It turns out there are already various factions within France fighting one another, including a siege on the Loire river in which a numerically superior Frankish force is unable to take a fort held by only a handful of their enemies. Askeladd sends in Thorfinn, older but still a kid, to make a deal with the besieging army.
Their general—who has a distorted cartoony design that resembles a fat toad, and with a weird voice to match—reluctantly agrees to ally with Askeladd’s men for the siege. The general’s out-of-place appearance is another sign that while Vinland Saga can be very realistic when it wants to be, it’s still depicting a highly stylized version of history and reality.
A more overt sign is when Askeladd’s men join the Frankish general’s armies in the siege the next morning, they come lugging their three boats on their shoulders and running at full speed; at least 25mph (the current record for human speed is Usain Bolt’s 27.8mph; he was not carrying a viking ship).
So yeah, even if the Vikings did carry their ships around on occasions when it was necessary to take land shortcuts, they certainly didn’t carry them that quickly, and I imagine when they were done carrying them they didn’t have enough energy remaining to not just fight a battle, but absolutely dominate in it.
Of course, challenging realism in this show is a slippery slope, so I’ll stop there, as it’s more plausible that after however many years Thorfinn has trained and killed for Askeladd, he’s become a finely-honed, ninja-like killing machine. There’s a long line of soldiers between him and their commander, but he cuts through them all like butter. Unfortunately, when he beheads the commander, the head falls into the lake, and the whole reason he went up there was to claim their leader’s head.
The Frankish general/prince was planning to betray Askeladd when it made the most sense to do so, but Askeladd betrays him first, pillaging the village of all treasure and leaving the worthless empty fort, and the victory, for the general.
Presenting the head of the commander, Thorfinn formally challenges Askeladd to the duel he’s owed once more, and Askeladd formally accepts…but only after they’ve escaped to safety. That means rowing their three big viking ships—likely overladen by treasure and other spoils—down a steep waterfall. Not only do the ships make it down without a scratch, but not a single gold coin spills out.
Despite all the action in this episode, it still felt rather static, in that Thorfinn and Askeladd’s unresolved conflict hung over everything, and the fact it was once again delayed despite Finn meeting the requirements feels like another artifical delay, for which their French excursion felt like so much window dressing. The comic-relief buffonish toad man and questionable physics further undermined the outing.