In Bergen, several forts were built to defend the harbour and the naval installations at Marineholmen and Wallemsviken from Swedish seaborne attacks.

This and the Howitzer L/14 cannons made Kvarven a very modern fort for its time, though it did not have to fulfil its intended use as the union with Sweden dissolved peacefully in 1905.

Norway attempted to maintain neutrality during World War II as well, but was invaded by the Germans in their Operation Weserübung on April 9, 1940.

When the fort finally opened fire at 3:58 in the morning, it only managed to get off a few shots through the fog at two torpedo boats and the cruiser Köln.

The fort first hit Bremse twice, then the MTB mothership Carl Peters [6] once, compelling both ships to break off their attempt to force their way into the harbour.

Two obsolete torpedoes from the Oscarsborg Fortress fired at 4:34 am[8] finished off gun-damaged German heavy cruiser Blücher, which finally sank at 07:30 am, just a short while after the Karven fort surrendered.

[5] The Brand was used with success by the Germans, with some immunity from air attacks because of confusion on its identity, during the next few days, and also was useful for the duration of their occupation of Norway.