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. The Bergen part of the operation was fronted by cruisers "Königsberg" and "Köln", with a total of 1,900 German soldiers. Kvarven fort was manned by 33 officers and 279 corporals and privates with an average age of around forty. The fort failed to open fire at the first German ships of the invasion force, mistaking the armed trawlers "Schiff 9" and "Schiff 18" for unarmed merchant ships. 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 ships did not retaliate, but sent a morse coded message in English saying “stop shooting!“. Only the third wave of German ships were taken under effective fire by Kvarven. The fort first hit "Bremse" twice, then the MTB mothership "Carl Peters" once, compelling both ships to break off their attempt to force their way into the harbour. After these ships, the cruiser "Königsberg" tried to break through and was hit by three shells: one beneath the waterline, one on deck and the third hitting the conning tower. "Königsberg" was barely saved due to its own counter fire and great technical difficulties up at the fort.