With Soviet and Polish troops entering Berlin in 1945, civilians moved into the Zoo tower to escape harm. Soviet troops (150th and 171st Rifle Divisions) attacked across the
Moltke Bridge covering the
River Spree. This was defended by German infantry and
rockets, who were under pressure from Soviet tanks crossing the bridge, until the heavier anti-aircraft guns from the Zoo tower could gain line of sight through the smoke. They destroyed the tanks and left the bridge covered in destroyed vehicles, which blocked further vehicles from crossing the bridge. The heavier
12.8 cm FlaK 40 anti aircraft guns obliterated Soviet armour, particularly when hitting it from the side. With thousands of
civilians crammed into the facility, conditions in the Zoo tower towards the end were close to unbearable; it was crowded and had little water, and the air was hard to breathe. As the Soviet armies advanced inexorably towards the centre of Berlin, around 10,000 German troops retreated to the Government district. The tower was never successfully assaulted; therefore, it was still able to provide anti-tank support to the defenders in the Government district. For example, during daylight hours on April 30, the Soviets were unable to advance across the open areas in front of the
Reichstag to attack the building because of heavy anti-tank fire from the 12.8 cm guns two kilometres away on the Zoo tower. Soviet troops, not wishing to attack the facility, arranged the surrender of the troops inside. Colonel Haller, negotiating on behalf of the tower, promised to
capitulate at midnight. This was a
ruse to allow for the forces in the
Tiergarten area to make a breakout through the Soviet lines and away from Berlin. This they did, shortly before midnight. The civilians then left the facility. == Resistance to damage ==