The heavy destruction of berlin, which occurred largely in the spring of 1945, was done mainly by:

E It was done mainly by the soviet union
The destruction occurred during the Battle of Berlin,  It was designated the Berlin Strategic Offensive Operation by the Soviet Union. scholars compound it as the ultimate demise of Berlin which culminated in the death of Hitler. The soviet red forces won the battle amidst wanton destruction of the city.

An elector in the electoral college.