Converting people to Esus w/o open borders.

[KillerClowns]

I'm playing a Sidar/Esus game, and I'm trying to convert my Svartalfar neighbors to the Council of Esus. I can't do an open borders deal because, frankly, they hate me. I tried using the Trojan Horse, but they had used their world spell, making it impossible for me to enter their cities. (Their city guards had hidden nationality, meaning I couldn't enter their square even with stealth units.) The Trojan Horse works fine, BTW, on cities not guarded by hidden nationality units (e.g. the Calabim cities). While I sent the Nightwatch to dispose of the hidden nationality Svartalfar guards in a fun little pseudo-war, some of their soldiers bumped into my Trojan Horse and destroyed it. I can't enter their cities with the Nightwatch either, because hidden nationality units can't capture cities, and I can't reveal their nationality without them getting removed. So now I'm stuck in a Catch-22:
I need to convert the Svartalfar so they like me.
I can't convert the Svartalfar unless they like me.
This makes sense for an ordinary religion, but shouldn't the Council have a few ways around a little thing like borders, other then my now-destroyed Trojan Horse?
I'm gonna try using Gibbon to force an open borders deal, or see if the undercouncil (we're both members) can force an agreement. But using Gibbon to get an open borders deal seems like overkill.
Before you ask, I tried revealing the nationality of my Nightwatch in their borders and them gifting them. Didn't work.
EDIT: Oh, and starting a real war would be suicide. They used their world spell early, but their new units are more then enough to send my soldiers to Arawn.

 

[loki1232]

You could convert to whatever the svartalfar religion is, get open borders, and then switch back to esus and spread your religion a bit.

 

[KillerClowns]

Problem solved, rather anti-climactially. When I promoted a mage to an archmage, I picked up Spirit III and cast Trust. Worked wonderfully.