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
Baltic Sea was an average of above sea level at Warnemünde and a maximum of above sea level in Warnemünde. In the last very heavy floods the average water levels reached above sea level in 1904, in 1913, in January 1954, on 2–4 November 1995 and on 21 February 2002. An arm of the North Atlantic Ocean, the Baltic Sea is enclosed by Sweden and Denmark to the west, Finland to the northeast, the Baltic countries to the southeast, and the North European Plain to the southwest. It is about long, an average of wide, and an average of deep. The maximum