As thread title, if one of your co-religionists is attacked in a holy war but also has a peasant revolt (religious uprisings do it too as I recall) you can't offer to join as defender of the holy war. It's been this way for ages but I can't see what the justification or indeed point is. I often end up chasing down the rebels myself if he's busy and then joining the war anyway to stop the enemy gaining ground but that's of course not always possible in time to save the day for the faith. Can't remember ever seeing this explained, anyone know?