One proposed upgrade would replace Oscarsborg's three 11-inch guns with six British 13.5-inch/45 guns. These First World War weapons would still be old in 1940, but their greater range and capability would give an attacker more to consider. The larger battery would also show that Norway had continued investing in its defence. Proper turrets could protect crews and shelter the mechanisms from the weather. Even the existing fortresses had a chance to damage or stop an attack when supported by mobilized infantry and organized local defences. Modest improvements and visible preparations could therefore influence whether an invasion was attempted at all.
Notable Point · 34:06-36:28
Six newer guns at Oscarsborg could have changed an attacker's calculations
A hypothetical replacement of Oscarsborg's three 11-inch guns with six British 13.5-inch guns illustrates how modernization could strengthen fighting capability and deterrence.