Even though it's not a two player alliance, I think the western triple (england, france, germany), Is the most powerful alliance in the game (even including if all four remaining countries allied). It immediately brings the game to the famous 'diagonal' stalemate line, and unless it's immediately combated, not later than '02, it is sure to bring all three nations into an arm's reach of winning. Granted, I've only ever seen it work once. Usually england and france stab germany for an easy few centers, and then germany helps the remaining powers, and, surprisingly, games like this often end in a turkish solo.