During the Second World War, all of Herdla was in effect a military base for the German Luftwaffe. The flat area "Herdlevalen" was considered a good place for an airport. The air base at Herdla was important to defend the west coast of Norway against Allied attacks. Many fortifications were built to hinder possibly invading forces. All civilians had to leave the island. In 1945 they came back to an island full of military installations.
Herdla was seriously considered as the site for Bergen's main airport. After the war the air traffic control for the Bergen area was placed at Herdla. However, in 1955, the airport was finally built at Flesland instead, since that would not require boat to reach it.