The treaty played a critical role in Bismarck's extremely complex and ingenious network of alliances and agreements which aimed to keep the peace in Europe and to maintain Germany's economic, diplomatic, and political dominance. The treaty provided that each party would remain neutral if the other became involved in a war with a third great power, though this would not apply if Germany attacked France or if Russia attacked Austria. Germany paid for Russian friendship by agreeing to the Russian sphere of influence in Bulgaria and Eastern Rumelia (part of present-day southern Bulgaria) and by agreeing to support Russian action to keep the Black Sea as its own preserve.