I am playing an online game as Britain. Literally every other player in the game - except Germany and France, who died, banded together to force a draw against me.

They hold all the territories right of the stalemate line, and while they have no way of breaching my defenses... The way the map is set, I can't hope to breach the stalemate line either.

This is making me incredibly frustrated. I have played alone against an alliance of five players, I managed to repel and defeat them conquering half of Europe myself, and now I can't seize the final victory because of the stupid stalemate line.

Frustrating! Especially given that this game has lasted 20 game-years already

Edit: Link to the map

https://imgur.com/a/lQWQ3qD