Soviet leader Joseph Stalin, who occupied the eastern side of Germany, prevented foreign help from other nations to fly into West Germany with supplies, the Berlin Blockade. Other nations wanted to help, so the Berlin Airlift was devised.
In the 1950s, West Germany benefited from economic success, so East Germans were looking to live in West Germany.
Construction of the 87 mile long Berlin Wall started in 1961, funded by the GDR and closing crossing points. Many Berliners were cut off from jobs. Money changed, the economies changed, and ideas changed between the two sides. The rift between East and West Germany remained, that rift separating families. Several died trying to cross the wall.
President Kennedy and President Reagan pleaded with the GDR to take down the wall.
Under international pressure, the GDR allowed travel between the two sides in 1989. In 1990, the Wall of Berlin fell.
Sources: Wikipedia, Cold War Flies, New York Times, German Missions in the United States
by Brigette W.