Answer:
The Berlin Blockade
Explanation:
The Berlin Blockade was one of the first crises we had at the start of the Cold War. During the occupation of Germany, the Soviets which was most likely assisted by their DDR (Eat Germany) puppet in denying the allies access to their zone of occupation within Berlin which was in East Germany. In response the Berlin Airlift started and on May 12, 1949 the blockade was lifted.
(The picture shows a map of occupied Germany. The Red is controlled by the Communist to show how easy it was for them to block access to Berlin [The yellow spot])