UF have 4,252 cities. All things considered, even if amazingly only 500 of them were bir nukes, and each nuke was 300 birs( a little less than average), and even if 200 nukes were out doing something, 300x300= 9000 birs...So in my opinion it is just your excuse for players being selfish. I reckon you guys with the amount of cities you have you could have broken that siege if everyone tried