When Germany annexed Klaipeda and the Klaipeda region in 1939. Construction of offshore and port protection batteries began and shortly after that Klaipeda gained fortress status.  Six „Fla-2“ anti-aircraft batteries were built for protection of airspace, and they formed a defensive ring. The battery consisted of a bunker made of reinforced concrete for crew members as well as ammunition. At that time, the most advanced anti-aircraft cannons were delivered to Pig’s Back battery in Smiltyne. These cannons were able to destroy targets on land as well as in the sea at a radius of 20 kilometers. In October 1944, this and other anti-aircraft batteries helped Klaipeda to withstand for 115 days – the longest out of all cities that belonged to Germany.