Ulm, Ulm and more Ulm !!!!

[Bowlingballhead]

Very strange. In my experience sending a spy into the enemy's home base is a surefire way to lose him. A mere 25 provincial defense has demonstrated itself time and again to me as a near-universal roadblock to spies.

[SurvivalistMerc]

That does often happen for one spy...

Try sending in about 4 or 5 at once, though. They are cheap enough that this isn't really cost-prohibitive. Tell me what happens then.

I think unrest helps to hide your spies...but that's just my supposition. And spies are better hidden than scouts with their stealth +20.