History of the North Sea great herring fishing industry resulting in Scotland becoming a European leader in that industry. During the First Schleswig War (1848–51), the Crimean War (1854–56) and the Second Schleswig War (1864), belligerents took steps to reduce or eliminate commerce in the North Sea by their enemies. In the first Schleswig War, Denmark was able to halt maritime commerce by Germany in the North Sea and in the second, imposed tolls on ships crossing through the Danish straits between the Baltic and North Seas. The Crimean War saw British and French expeditions sent into the Baltic to prevent Russian ships' egress into
History of the North Sea dumped in the Skagerrak and the Baltic, conventional weapons (grenades, mines, bazookas, and cartridges) were sunk in the German Bight. The estimates vary widely but it seems to be clear that more than a hundred thousand tons of munitions were sunk. The Maunsell Sea Forts were small fortified towers built in the Thames and Mersey estuaries during the Second World War to help defend the United Kingdom. One of which on HM Fort Roughs is now occupied by the controversial Principality of Sealand. Post Second World War period, the North Sea, bounded entirely by NATO allies became completely peaceful whilst