History of the North Sea the North Sea though they saw little action. The Austro-Prussian War (1866) resulted in Prussia's gaining full control of the Kiel Canal, allowing their Baltic ports access to the North Sea. France declared war on Prussia 19 July 1870 which initiated the Franco-Prussian War (1870–1871). The French Navy was, at the time far larger and superior to the North German Federal Navy, the Navy of the North German Confederation. Though the French did take a number of merchant ships bound to and from North Germany, shortages of manpower and coal, as well as conflicting orders, made the attempted blockade of
Danube–Black Sea Canal Danube–Black Sea Canal The Danube–Black Sea Canal () is a navigable canal in Romania, which runs from Cernavodă, on the Danube river, to Constanța (southern arm, the main branch), and to Năvodari (northern arm), on the Black Sea. Administrated from Agigea, it is an important part of the European canal system that links the North Sea (through the Rhine–Main–Danube Canal) to the Black Sea. The main branch of the canal, with a length of , which connects the Port of Cernavodă with the Port of Constanța, was built between 1976–1984, while the north branch, known as the Poarta Albă –