Heligoland places British observers, fighters, and light naval forces close to the routes Germany used in Operation Weserübung. The island could provide Denmark with warning of an invasion and allow the Royal Air Force to attack bombers, transports, and gliders supporting the assault. Denmark's historical rescue of Jewish people offers an analogy for what warning and rapid movement can enable. That example supports the scenario's warning-and-mobilisation argument without implying that the 1940 invasion would simply repeat the later rescue. If German naval forces can reach only southern Norway, the central and northern landings become much less likely and Norwegian troops can concentrate differently. Narvik and other northern objectives might then remain in Allied hands while the Royal Navy supports the Norwegian response, making the island relevant to the land campaign as well as the naval war.
Notable Point · 2:16:36-2:20:27
How Heligoland could disrupt the invasions of Denmark and Norway
A British observation and air base close to Germany could warn Denmark, intercept airborne forces, and make Germany's central and northern landings in Norway much harder to execute.