Kristiansand was attacked by German naval forces and the Luftwaffe during the Operation Weserübung on 9 April 1940. The naval forces met fierce resistance from Norwegian coastal artillery at Odderøya. Bombs and grenades also hit the downtown and the 70 meter high church tower of the Kristiansand Cathedral was hit by accident. The third attack attempt on the city succeeded because a signal flag was confused with a French national flag and the misunderstanding was not discovered until it was too late. The city was occupied by a force of 800 men.