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 watchtower, Börgerende Baltic Sea watchtower, Börgerende The Baltic Sea watchtower () in Börgerende is an old watchtower that belonged to the Coastal Brigade ("Grenzbrigade Küste") of the East German Border Troops. As a maritime border observation tower (of type BT 11) it belonged to a series of originally 27 towers of this type on the Baltic Sea coast of East Germany, of which two have survived. The other remaining tower is in Kühlungsborn. The tower is located right next to the beach. The East German border soldiers had the mission of observing shipping movements on the Baltic Sea and identifying escape attempts.