The Danube is a river in Europe, second longest and one of the principal traffic arteries on the continent. It is the only major European river to flow from west to east. It
rises in the Black Forest region of Germany and flows in a generally easterly direction, emptying on the Romanian coast into the Black Sea. The delta of the Danube is a
region of desolate marshes and swamps, broken by tree-covered elevations. The Danube is navigable by ocean vessels to Braila, Romania, and by river craft as far as Ulm
in Germany. About 60 of the approximately 300 tributaries of the Danube are navigable. The principal ones, in the order in which they merge with the Danube, include the
Lech, Isar, Inn, Morava, Vah, Raab (Raba), Drava, Tisza, Sava, Siret, and Prut. Important cities on the river include Ulm, Regensburg, and Passau, in Germany; Linz and
Vienna, in Austria; Bratislava, Slovakia; Budapest, Hungary; Belgrade, Serbia; and Galati and Braila, in Romania. Canals link the Danube to the Main, Rhine, and Oder
rivers. The Danube Valley between Linz and Vienna, Austria, is noted for its beautiful scenery.
The Danube has always been an important route between western Europe and the Black Sea. Early in the Middle Ages Goths, Huns, Avars, Slavs, Magyars, and other
migratory peoples crossed the Danube on their way to invade the Roman, and later the Byzantine, Empire. It served as an artery for the Crusaders into Byzantium
(Constantinople) and from there to the Holy Land; later it eased the advancement (beginning at the end of the 14th century) of the Ottoman Turks into western and central
Europe. In the 19th century it became an essential link between the growing industrial centers of Germany and the agrarian areas of the Balkans. By the terms of the Treaty
of Paris (1856), terminating the Crimean War, a European commission was established to control the delta. The commission made a number of changes in the delta and in
the lower reaches of the river beneficial to navigation. In 1890 the Austrian government began a series of improvements in that part of the river known as the ! Iron Gate.
The Treaty of Versailles (1919), concluding World War I, confirmed the European commission, and set up another one to control the Danube above the delta. During
World War II the commissions were abolished by Nazi Germany, which controlled all of the river from 1940 to 1944. After the war the Communist-bloc nations bordering
the river formed a new Danube Commission, headquartered at Budapest.
Cities on the Danube River: Passau, Linz, Vienna, Budapest, Novi Sad, Belgrade (Beograd), Rousse, Braila, Galati, Tulcea,