The Whole World In Your Hands

You send out the nukes, and soon London is a wasteland. You march triumphantly into the capital, and are crowned Duke of England (the Queen survived the blasts. But she bowed).

And then you are in turn blown up. Right before you were turned to smithereens, you were able to read the label on the nuke.

France! France was your ultimate undoing! Since when do they fight anyone? Oh well.