From the campaign:
Thank the Gods! Another successful raiding voyage! You will be seen as heroes to return home with so many spoils. But one big problem awaits. You and all the other Viking lords have sworn fealty to a chieftain who takes, by right, half your wealth when you go viking and return with plunder. Thankfully, this Jarl only targets the one among you who has gained the most, the one he fears the most. If you acquire and hold on to the most Wealth and overcome all opposition, you will become the next great chieftain and win the game!