I bought a chapter pack called "Calling the Banners", and I am not sure how to play the Baratheon card "Compelled by the Crown".

Choose one participating character on each side during an intrigue or power challenge.

Remove all other characters from the challenge.

Then stand all characters with banner attachments.

Can one of you give me an example of how this works. It seems straightforward, but I want to make sure I am not missing something. Thanks.

It works exactly the way you think it does.

After defenders are declared, you choose 1 attacker and 1 defender, effectively making the challenge a 1-on-1 fight. If any Bara characters have attachments with the Banner trait, stand those characters.