Before the battle

As the political situation was chaotic, the 64-year-old commander, Oberst (Colonel) Birger Eriksen, had not received any clear orders and had received no notice as to whether the approaching warships were German or Allied. He was well aware that Norway was officially neutral, but that the government was inclined to side with the British in case of direct Norwegian involvement in the war.

Apart from the officers and NCOs, almost all the soldiers manning the fortress were fresh recruits, having only been conscripted seven days before, on 2 April. Because of the influx of 450 fresh recruits, the fortress\’ naval mines were not deployed on 9 April. Part of the recruits\’ training was to lay the mine barrier, a process planned for a few days later.

Torpedo battery

The commander of the torpedo battery at Oscarsborg had at the time of the battle been on sick leave since March 1940. Due to this, the retired Kommandørkaptein (Commander Senior Grade) Andreas Anderssen [no], who lived in nearby Drøbak, had been assigned as temporary commander for the battery. As an unidentified flotilla started forcing its way past the outer fortifications in the south of the Oslofjord, late at night on 8 April, Oberst Eriksen called Anderssen in and had him come down to the fortress. Kommandørkaptein Anderssen donned his old uniform and was transported by boat over the fjord to the torpedo battery. Anderssen would show himself worthy of the important task of leading the fortress\’ most lethal weapon system; having first served at the torpedo battery in 1909, he knew the ageing weapons intimately. When Anderssen had been called back into duty a month previously, he had been a pensioner for 13 years, having originally retired from his post as commander of the torpedo battery in 1927. The battery had three torpedo tunnels which could fire six torpedoes without reloading and a total of nine torpedoes were stored and ready for use.