Chancellor Bismarck's imperial foreign policy basically aimed at security and the prevention of a Franco-Russian alliance, in order to avoid a likely Two-front war. The League of Three Emperors was signed in 1873 by Russia, Austria, and Germany. It stated that republicanism and socialism were common enemies and that the three powers would discuss any matters concerning foreign policy. Bismarck needed good relations with Russia in order to keep France isolated. Russia fought a victorious war against the Ottoman Empire from 1877 to 1878 and attempted to establish the Principality of Bulgaria, that was strongly opposed by France and Britain in particular, as they were long concerned with the preservation of the Ottoman Empire and Russian containment at the Bosphorus Strait and the Black Sea. Germany hosted the Congress of Berlin in 1878, where a more moderate peace settlement was agreed upon.