[@Vhagar] While I understand your point. (I really do) and it's obvious you would have won, but Bear Island would expect and be ready for an attack at any time of day or night in such this case. Their 'Household' guard aren't just their guards they are literally their raiding party enforcers. When you hit Bear Island as a Iron Islander you -know- it's going to be tough. Somehow managing to sneak your ship into shore, and then with all those weapons not make a single sound to tip off a defender struck me (or is rather new to the RP) as seriously off. 

I highly doubt also that the entire palisade is only guarded by those 'meager' men as you suggested as again the Mormonts are ready for an attack, i'm -sure- nighttime raids have happened before and i'm -sure- that the Mormonts would be ready. Again, my opinion but you seem to underestimate Northern fighters a great deal. As a very large lover of unorthodox and asymmetrical warfare I have to say that of the two scenes that seem to be conflicted between you two that your scenario makes a whole lot less sense than Mr. Stark. I also don't blame you for that as not any people can imagine being shot with hundreds of arrows every 50 yards or such down a river with obstacles and probable fire. I think the GM was lenient on you because if a real Ironborn navy tried to sail into hostile lands like that with the forest surrounding them KNOWING how skilled the Northern Rangers are then they deserve to get obliterated because that's what they would have been. By the time you reached the lake you would maybe MAYBE have enough men to put up a fight, but Northern ships already proven to be stronger than your own would kill even more and arrows once again would take down another score. Who do you plan on fighting with? Your corpses? 

Regardless the GM has spoken I just urge you to drop it before it's revoked and you lose more.