Suck it up...Brits like to call that "keeping the balance of power in Europe".
Luckily for U whenever you are already in a war other countries wont join in (if so the ai would always defeat the player) so you can defeat them piece meal (which is a luxury Spain in the XVII century, France in the XVIII or Germany in the XX Century didnt have).
Use the good ol' tactic of letting the ai advance and then encircle them. You can make defeats of 1million+ men like the germans did with the anglo french in France in 1940. That is how I did manage to defeat russia that DOWed my mighty German Empire shorthy after the three hurra's. After you satelite Russia, other powers will be more reluctant to DOW you as that would mean Russia joining also in the war(which I had supplied with a lot of military techs hehehehe

).
The only problem I had in my prussia game was the total aniquilating supperiority of the Royal Navy, but even then I had been the architect, my glorious industrial might produced all the steam ships the british did ever need to build their huge fleet. As they were eternally at war with me, that meant that I couldnt use naval movement during the whole game.

o
Marvellous strategy marvellous!:rofl: