The Grand Alliance agreed to divide Germany and its capital Berlin into four separate occupation zones (1945). These were administered by the Soviet Union, the USA, France and Britain.
The division was only meant to be temporary but it ended up lasting many years.
The Allied Control Commission (ACC) was the Central Organisation for the 4 zones. There was soldiers on the streets, and in Berlin, military checkpoints between zones.
There were disagreements between occupying powers. The three western countries and the soviet union had a different way of looking at Germany.
The Soviets wanted to take as much materials as possible back to help rebuild the Soviet Union
The western countries wanted to build up Germany's economy
In March 1948, talks between foreign ministers of the occupying powers broke down and the soviets stormed out.