The agreement to make Constantinople a Free City was not in the convention proper, but in an even more secret supplementary agreement. These documents shed some light on the aims of the
Russian Tsar. Like his predecessor
Nicholas I, Alexander II saw an opportunity of finally realising the
Greek Project. This was a plan originally proposed between
Catherine the Great and
Joseph II to partition the Ottoman Empire and restore the Greek
Byzantine Empire. Turkey's power would be finally broken, and the Balkans would become the sphere of influence of the
double headed eagle empires of Austria-Hungary and Russia (both states had adopted the double headed emblem of the
Byzantine Empire the symbol of the last Byzantine dynasty, the
Palaiologos). For Austria-Hungary, it was important that Russia did not attempt to create a large Slavic state (
großen, kompakten, slawischen Staat) in the Balkans that would create problems with the Slavic nations within the monarchy. Even in a convention signed with
Great Britain on 18 March 1877, there was an emphasis on Russia not creating a large state in the Balkans. The Budapest Convention was one of several secret agreements with which Russia sought to secure the support or at least the neutrality of Austria-Hungary. In addition to the
Reichstadt Agreement a year earlier there was a supplementary convention to this treaty in March 1877. == Aftermath ==