Socialist Federal Republic of Yugoslavia
Regarding rivers, the Danube was navigable throughout its entire course in Yugoslavia, linking the ports of Belgrade, Novi Sad, and Vukovar with Central Europe and the Black sea. Long stretches of rivers Sava, Drava and Tisza were also navigable.
Internationalization of the Danube River
On December 28, 1854, during the Crimean War (France, Britain, Sardinia, and Turkey versus the Russian Empire), the allies sent to Russia a note urging the internationalization of the river as one of the bases for a peace treaty:
. . . it would be desirable that the course of the Lower Danube . . . be withdrawn from the territorial jurisdiction. . . . In every case the free navigation of the Danube could not be secured if it be not placed under the control of a syndical authority, invested with the powers necessary to destroy the obstructions existing at the mouths of the river, or which may hereafter be formed there.