They should have turtled up Thulsoma style. Then again, everything I keep hearing about Madina suggests that it would have been next to impossible to get the other lords to contribute anything to the effort. Level 7 walls with 8k CS behind them would have broken most armies, though that last one was so big, who knows. We took down Valkyrja with about that much defending strength (maybe more even, can't quite remember anymore) and we had 40k CS. And the battle wasn't that difficult. 30k CS, we might still have managed, and so might have Aurvandil.