German WWII heavy cruiser.
Tonnage: 18000 (but officially claimed to be 12200)
Armament: 8 x 203 mm cannons
Launched: August 15, 1935
Length: 205,9 m
Breadth: 21,3 m
The sinking of Blücher
Blücher, being the newest large war ship in the German Navy at the time, was a central piece in Adolf Hitler's plan to invade Norway on April 9, 1940 (Operation Weserübung). It was the flag ship of attack force 5, set to invade Oslo, and contained commando soldiers with important objectives in the capital. Among these were King and government, the plan being to seize them and force a quick surrender.
Blücher sailed into the Oslo fjord in the early morning, and was detected and attacked by the old, "obsolete" coastal fort Oscarsborg. Blücher was hit at close range (1400 m) by two of the main cannons, "Moses" and "Aron" (Krupp 280 mm cannons from 1892). It was then sunk by two torpedoes. At 0621, the ship disappeared, bow first, into the Oslo fjord.
Approximately 1000 soldiers and sailors died on Blücher, while about 1400 managed to get to the eastern shore - alive but unable to fight.
The consequence for the war effort
The rest of the invading force turned around and landed further down the coast. Instead of Oslo being invaded early morning, it wasn't German-controlled until the afternoon. By that time, the King and the government had managed to flee. The King ended up retreating to England, where he spent the rest of the war.
This allowed the government to declare that the invasion was a breach of neutrality, and allowed the King to veto the Quisling government. It is therefore an important event in Norwegian war history.
Blücher today
The ship has remained in the Oslo fjord for 54 years. It was well known that the ship was leaking oil, testified by the constant flake of oil called the "Blücher patch". The ship lay at 100 meters. Due to the heavy cost and the technical difficulties, nothing was done for a long time.
During 27 days in October-November 1994, the wreck was emptied of close to all the remaining oil (approximately 1000 liters). 18 divers participated in the job that turned out too complicated to perform with mini-submarines. 12 special ships on the surface were ready to clean up the extra leakage this job caused. Today, Blücher is no longer considered an environmental threat, although some oil is still trickling out of it.
Sources:
1. NorgesLexi, War History, http://norgeslexi.com/krigslex/krigslex.html
2. Norwegian Foreign Department, http://odin.dep.no/ud/
3. http://www.skovheim.org/bluch.htm
4. http://www.deutsche-kriegsschiffe.de/Schiffe/bluecher.htm : Contains pictures of Blücher