Divided Germany—A Brief History
To stave off any attempts by Germany to remilitarize and seek war for a third time, the Allied powers at the Potsdam Conference opted to divide the country and the city of Berlin into four occupational zones – one for each of the Allies. In 1949, the zones controlled by the United States, Great Britain, and France combined to form the Federal Republic of Germany (commonly known as West Germany), while the Soviet Union’s zone became known as the German Democratic Republic (East Germany). In 1955, Communist-controlled Eastern Europe (including East Germany) formed the Warsaw Pact when Western Europe (including West Germany) was folded into the North Atlantic Treaty Organization (NATO). On August 13, 1961, construction began on the Berlin Wall, which separated East Berlin from West Berlin, effectively halting emigration between the two areas, cutting off families from each other, and preventing workers from reaching their jobs.
Over the next 28 years, the Wall underwent four different stages of development – a basic wire fence, an improved wire fence, a concrete wall, and a border wall. During this time, around 5,000 East Germans successfully escaped into West Berlin, around 200 were killed in their attempts, and many more were injured.
Wikipedia (“Germany,” “Berlin Wall”)