I'm confused. If you enforce peace against your colonial nation won't you be at war with them? Which would make no sense so what is the result?
Normally you can only Enforce Peace on the attacker, where you select the defender you want to protect.
You are not called into the wars of your Colonial Nations automatically when they are fighting other CNs or Natives. If you want to intercede in the war, you have to Enforce Peace.
If your CN was DOW'd - i.e. they are the defender - then the procedure is as normal; you Enforce Peace on the attacking warleader, and choose to protect your CN.
If your CN was the one who DOW'd - i.e. they are the attacker, then you still Enforce Peace on the other side - it would make even less sense to Enforce Peace on your own CN, just because they are the attacker! So in this scenario, you are Enforce Peace'ing on the
defender.
So:
I am Great Britain. My CN is Thirteen Colonies. Thirteen Colonies is attacked by French Canada. I want to join this war. I Enforce Peace on the Diplomacy screen of French Canada (the attacking WL), and choose to protect Thirteen Colonies. I join the war on the side of Thirteen Colonies. This is a normal Enforce Peace.
I am Great Britain. My CN is Thirteen Colonies. Thirteen Colonies attacks French Canada. I want to join this war. I Enforce Peace on the Diplomacy screen of French Canada (the
defending WL), and choose to protect Thirteen Colonies. I join the war on the side of Thirteen Colonies. This is the special case for defending Colonial Nations. The operations performed are identical as for the first case, but it's unusual because this is the only time in the game when I Enforce Peace on the screen of a
defending nation.
And apparently all this applies to a Protectorate when they DOW another nation, too. (There's no need to Enforce Peace when your Protectorate is themselves DOW'd, because you'll be auto called in that situation.)
