I, with my 4 allies (a selection of Swedish Jarls), all of whom were IN Alba at the time, had just shy of 7k, they (Alba) had 3k. The last thing I wanted was to lose, because doing so meant that Alba would 'take back' Iceland as they had decided I could no longer be trusted to keep it (!?), so brought in all my allies.

My allies, rather than actually being useful, opted to simply take in the sights of the Scottish highlands, and somehow my holding his Capital and 2 other counties pales in comparison to them having taken Hjaitland (NOT my Capital), after they immediately ran off into the middle of the ocean before doing a handbrake turn and going after the northern isles, while I was waiting for my allies to sail over.

Needless to say they (Allies) continued to sightsee while Alba managed to secure an alliance with Lotharangia, whom had developed super-speed and within 3 weeks of accepting, were up in Iceland as my courtiers and council happily impaled themselves on Lotharangian swords...

Edited for clarity