The Battle Balloon is a type of fixed defensive installation, consisting of a helium- or hydrogen-filled dirigible, moored by steel line, carrying a .50-cal machine gun.

The Battle Balloon is deployed to provide anti-aircraft cover of fixed installations. However, the balloon itself is unarmored and vulnerable to enemy fighter attack. Battle balloons, therefore, work best when supported by other anti-aircraft defences. However, battle balloons can be deployed much more rapidly than ground turrets, and are therefore common at temporary or new facilities.

Battle Balloons have been deployed by both the British Empire and the Black Hats pirate gang.