Oscarsborg Fortress

Drøbak, Norway

The narrows at Drøbak, called Drøbaksundet, is a natural point for the naval defence of Oslo, the capital of Norway. The first defences were constructed during the reign of Christian IV of Denmark and Norway and were ready in 1644. The fortifications were however not involved in battle during the Hannibal War. After the war the fortifications were dismantled, and only resurrected for a short period during the 1814 war with Sweden.

Around 1830 the discussion started for a renewed fortification of the Drøbak Narrows and the first stage was ready in 1848, the next in 1853. The name of the fortress was given by royal resolution on 23 August 1855 after a visit by the Swedish-Norwegian King Oscar I.

By the end of the 19th century the art of war developed rapidly and the new fortress was soon obsolete. The tension was also growing between the two countries in the union and so the Norwegians decided to upgrade the fortress. From 1890 new improved German guns were installed, an underwater barrier was built in 1874–79, and an underwater torpedo battery was constructed. The main armament was three 28 cm calibre guns manufactured by Krupp. There were also a number of guns with smaller calibres on the mainland. An underwater barrier went from the main islet of Kaholmen and south-west to Hurum on the western side of the fjord, thus making it impossible for large vessels to sail west of the fortress.

Having been constructed in 1898–1901, and taken into service on 15 July 1901, the underground torpedo facility remained one of the few Norwegian defence installations unknown to German military intelligence at the point of the 1940 invasion. The battery was one of two in Norway and it was designed to launch its torpedoes from under the water level. At Oscarsborg the torpedo battery is a concrete construction inside a cave mined into the rock of the North Kaholmen island.

When Norway was invaded on 9 April 1940, all of the fortress' armament was over 40 years old, and of German origin. Both the guns and the torpedo battery worked flawlessly when Oscarsborg encountered one of the German invasion flotillas; they sank the heavy cruiser Blücher, and threw back the German naval force heading for Oslo, thus managing to save the Norwegian King and government from being taken prisoner. The fortress was returned to Norwegian control on 12 May 1945 when Captain Thorleif Unneberg took command of the fortifications and raised the Norwegian flag following the capitulation of all German forces in Norway four days earlier.

During the Cold War Oscarsborg formed a last line of defence for the capital city, with the underground torpedo battery remaining secretly active up until 1 January 1993, having been modernized in the 1980s. After the deactivation of the last weapons systems, the remaining military activity on Oscarsborg consisted of the Coastal Artillery officer training programme. The officer school was officially shut down in 2002. The fortress is now largely a civilian resort and attraction, open for visitors. The scenic surroundings is much used for conferences and excursions. Visitors take a short motor launch trip from Drøbak.

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Details

Founded: 1846-1855
Category: Castles and fortifications in Norway

Rating

4.6/5 (based on Google user reviews)

User Reviews

Tom Campbell (2 years ago)
This was an excellent place to visit. Would highly recommend, such excellent history. Also the escape room was with out doubt the best one I have ever taken part in.
Kseniia Snikhovska (2 years ago)
Interesting, but more like one time to see. Food on island is not good, so it is more like picnic, sightseeing and swimming destination
Bee Dee (2 years ago)
great historical importance; an important battle. access to nearby town by ferry. good food. great museum. lovely marina.
Sebastian Haugland (2 years ago)
Exciting place with a lot of history. A decent hotel, Restaurant and other activities. It also is a good place for a historic walk around the Island.
Bartlomiej Skorowski (2 years ago)
Great place, but needs time to see most of the island. With kids it took 5 hours. Fun, food, walk, visiting museum and taking photos. There is a path that goes around the island. Beautiful landscape. Fortress it self has a museum inside. It is worth to see it. Entry for free. Movies in museum are played in Norwegian and English language. Very interesting history of Norwegian defense. I recommend to choose not windy day as it can blow quite strong there. A bit expensive to get a boat as it goes between the two different areas but it is definitely worth it.
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