Can you declare a crusade on an Orthodox city?

[rvg]

In many games that I've played I've never seen that as an option, but would like a second opinion to confirm it. Is it possible or not?

[Patricius]

No.

Oddly crusades against Catholic cities are eminently possible.

[Doug-Thompson]

Oddly, no, although Muslims can declare Jihad on either Catholic or Orthodox, and bandit-controlled cities, too.

Also, I believe the only Catholic cities that are vulnerable to Crusades are those belonging to excommunicated factions.

[Rhyfelwyr]

I've noticed Rebel cities being Crusade targets. Cagliari once became a Rebel-held crusade target due to it being so isolated prior to the patch that fixed naval invasions, as a heretic had spawned in the place and had the religion at well over 50% Heretic.

[lobo76]

Rebels can be targeted. I liberated Antioch after a crusade in my French campaign. Too lazy to administer a city so far away, I give it to HRE to try to buy a ceasefire (which didn't work out)... but I gifted it to them anyway... AFTER I sold all the buildings in the city for $$$.

It rebel right after HRE took over, and my cardinals become the pope soon after. Looking at my list of crusade targets, Antioch is included.

[ReiseReise]

Rebels can be targeted. I liberated Antioch after a crusade in my French campaign. Too lazy to administer a city so far away, I give it to HRE to try to buy a ceasefire (which didn't work out)... but I gifted it to them anyway... AFTER I sold all the buildings in the city for $$$.

It rebel right after HRE took over, and my cardinals become the pope soon after. Looking at my list of crusade targets, Antioch is included.

A city simply being rebel is not sufficient cause for a crusade. The reason Antioch was on the list was because it was rebel AND muslim religion.

In order to be a Crusade target, a city must be one of the following
rebel and (muslim or pagan religion)
Controlled by Muslim faction AND have certain % of catholic or meet other unknown pope criteria.
Controlled by an excommunicated faction

Not every city meeting these will be on the list, there are only so many spots and the pope chooses them for weird reasons.

[rvg]

Yeah, I never quite figured out the logic behind Popes' choices for crusade targets, although Jerusalem is always on the list, as usually are the capitals of excommed factions.

[uanime5]

The Pope is more willing to call Crusades against settlements with a large number of Catholics that are controlled by a non-catholic faction. If you send enough priests to an Orthodox settlement and raise the number of catholics the Pope may call a crusade against them.