Ostpolitik (German for Eastern Politics) describes the politics of the "Change Through Rapprochement" principle — as verbalized by Egon Bahr in 1963 — by the effort of Willy Brandt, Chancellor of the Federal Republic of Germany (West Germany), to normalise his country's relations with Eastern European nations (including the German Democratic Republic, or East Germany).
The proper term is in fact Neue Ostpolitik (German for New Eastern Politics), to set a contrast to the former Eastern Europe politics of the Christian Democratic governments until 1969. The Christian Democrats under Konrad Adenauer and others tried to ignore and isolate the communist regime of East Germany, while Brandt's Social Democrats tried to achieve more freedom for East Germans by a certain degree of collaboration.
The Federal Governments were dominated by the Christian Democratic Union from 1949 to 1969. These governments refused every contact to the GDR government due to its undemocratic character, and the Hallstein Doctrine threatened to cease diplomatic relations with every country that established diplomatic relations with GDR. The first case of applied Hallstein Doctrine was Yugoslavia that accepted a GDR ambassador in 1957. In the 1960s it became obvious that this policy would not work forever: When the Federal Republic in 1965 established diplomatic relations with Israel, Arabic countries established those with GDR, following the break off between the Federal Republic and those countries.
The new Ostpolitik of Social Democrat Willy Brandt, Chancellor since 1969, entailed the idea that the old politics did not help to undermine the communist regime or even lighten the situation of the Germans in GDR. Brandt thought that collaboration with the communists will foster German-German encounters and trade and undermine the communist government on a long term.
He stressed out nonetheless that his new Ostpolitik does not mean to neglect the close ties of the Federal Republic with Western Europe and the United States; actually, the Federal Government had repeatedly been urged by US politicians like Henry Kissinger to be more flexible, and also other West European countries entered a period of more daring politics directed to the East. When the Brandt government came to power in 1969, the same politicians now feared a more indepedent German Ostpolitik, a new "Rapallo". France feared that the Federal Republic would become more powerful after a détente, Brandt gained the French endorsement by holding out German financial sacrifices concerning the European agricultural politics.
The most controversial agreement was the Basic Treaty of 1972 with GDR. The Federal Republic agreed on establishing diplomatic relations with GDR. Chancellor Brandt repeated his statement of 1969, that although two states exist in Germany, they can not be a foreign country to each other.
The conservative CDU opposition party in the Federal Parliament refused the Basic Treaty because they thought that the government gave away some Federal positions too easily. They also critized flaws like the unintentional publishing of the Bahr-Papier, a paper in which Brandt's right hand Egon Bahr had agreed with Soviet diplomat Valentin Falin on essential issues.
The Brandt government, a coalition of Social Democrats and Free Democrats, lost a number of parliament members to the CDU opposition. In April 1972 it even seemed that opposition leader Rainer Barzel had enough support to become new Chancellor, but in the parliamentary decision he came two votes short. Later it was found out that GDR had paid those two CDU seats to vote against Barzel. New general elections in November 1972 gave the Brandt government a victory and on May 11th 1973 the Federal Parliament approved the Basic Treaty.
According to the Basic Treaty the Federal Republic and GDR accepted each other's ambassadors, called "permanent representations". It also made it possible to the two German states to become member states of United Nations.
In 1982 the CDU leader Helmut Kohl became German Chancellor, but did not change Germany's policy towards the GDR. In 1983 even Franz Josef Strauß, who had fiercely fought against the Basic Treaty, agreed to give a one billion loan (initiated by Kohl) to the GDR.
Later agreements in the period of Christian Democrat Helmut Kohl (since 1982), although dealing with similar issues and having similar goals, are not considered to be "Ostpolitik".