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
Geology of the Baltic Sea years of existence connected to the White Sea through Karelia due to the isostatic depression caused by the ice sheet of the earlier Saalian ice age. Little is known about the Baltic Sea during the oscillations of the Weichselian ice age, the last glaciation. The first Weichselian glaciations, corresponding to MIS 5b and 5d, penetrated parts of the Baltic Sea depression from north to south but did not got south beyond the Åland Islands. The Weichsel ice sheet reached northern Denmark about 65–60 thousand years ago. When the last ice sheet began to retreat north from the Baltic Sea depression