The battle bunker is a simple combat structure which can hide 5 soldiers who can fire from it, used by Soviets during War of the Three Powers.
Battle bunkers are simple but useful buildings. Due to alterations in reality precipitating from the removal of Einstein from the timeline, these bunkers were no longer constructed through the Construction Yards. Instead, Soviet Combat Engineers who were given the basic tools needed to construct it in a cost efficient manner.
The new-era Battle Bunkers are still garrisonable by five infantry units, as before; however, they take only one "building tile" of space. They cannot, it seems, fire over walls any longer, though. And, while they retain their excellent characteristics for durability, there are weapons, such as the Desolator Airstrike (which is not often a threat, since, like the Battle Bunker, Desolator Airstrikes are a Soviet protocol.) However, Imperial Warriors with their Beam Swords out can clear a Bunker like any other building, and Peacekeepers who get too close (rare, because two Conscripts in a bunker can seemingly hold off Allied infantry for ages) also clear them out; worse yet, after it has been cleared, the enemy can take it over and use it themselves.