Quote Originally Posted by A Very Super Market View Post
If you actually moved your army away from siege, then attacked again, and the mobs came back it would still be reasonable. But the game sometimes glitches and acts like you broke the siege when the defenders sally.
That would be a bug.

If you don't take the city, it is reasoned that defenders would continue resisting, forming mobs.

If they sally, they are attacking you...Still...it could work either way, you should be able to just take the city after winning a sally.