Hehe, well, here goes
I was doing fairly well, and got to colonizing America and the Caribbean as England. I'd conquered Scotland and Ireland long ago. The only other nation in the America's were the Dutch. Spanish, Port's and French were nowhere to be found. Anyway, being as I am, I got an alliance with the Dutch, since I didnt have many troops to spare for the colonies, so i wanted to avoid conflict
The Dutch then, in all their wisdom declared war on France, so I thought "Hell, the Dutch will kick their asses" (seeing as the Dutch had very many troops in Holland at the time)
What happens next?
Holland is completely over-run by the French, who use the 'land-bridge' between Dover and Calais to attack and bring havoc to the south coast

I had to surrender Kent, Wessex, Cornwall, Bristol and Wales
My Problem with the game...
MONEY!!! I have absolutely no skill in managing money, and so I can very rarely amass a large enough army, even on the easiest difficulty settings

(Although this particular game was on Normal/Normal)