Anti-aircraft gun

The anti-aircraft gun (or AA gun) was an Allied anti-aircraft defense during the Second World War.

Background
The AA Gun is an anti-air flak weapon fitted with a set of four powerful 3.7cm cannons paired with an automated fire-control and aiming system. Due to the complexity of the targeting system and the gun and chassis employed, its targets are limited strictly to aircraft. Moreover, the automation heavily relies on sufficient amounts of power from the power grid to keep them online. Though a powerful and reasonably cheap weapon system, their relatively short range somewhat limits their firing potential. However, multiple batteries of AA Guns proved devastating especially when strategically placed around the base.

Game structure
The AA gun dealt twice the damage output of the Soviet SAM site, but has slightly less range and consumes much more power, making it the hardest hitting anti-air defense turret in the game. However if the base is powered down, the turrets won't function, so Allied players need to keep their bases powered at all times.

It cannot harm ground-based units, or interfere with them in any way other than potentially distracting them from attacking a more valuable target (e.g. the Construction Yard).

Legacy
In a twist of irony, the Allies replaced the AA Gun with the Patriot missile system during Third World War, which is similar to the Soviet SAM site.