This is the second time I've gotten stuck at the same point in this quest. I've got to defeat Alduin but the Jarl of Whiterun will not let me use Dragonreach to capture a dragon while the civil war is raging. I talked to the Greybeard Arngier and he has agreed to host a peace council if Ulfric and Gen. Tullias agree to attend. I talked to Ulfric and he agreed to attend.
Here's where I'm having the problem. Every time I talk to Gen. Tullias, all he say is 'Am I willing to join the Imperials?'. I can't get past that. I get no other conversation out of him.
I've even gone back many saves ago and restarted other quests leading up to this quest, but always the same.
Help. What am I doing wrong?