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 campaigns (1939–45) Baltic Sea campaigns (1939–45) The Baltic Sea Campaigns were conducted by Axis and Allied naval forces in the Baltic Sea, its coastal regions, and the Gulf of Finland during World War II. After early fighting between Polish and German forces, the main combatants were Germany and Finland, opposed by the Soviet Union. Sweden's navy and merchant fleet played important roles, and the British Royal Navy planned Operation Catherine for the control of the Baltic Sea and its exit choke point into the North Sea. While operations included surface and sub-surface combat, aerial combat, amphibious landings, and support of large-scale ground