On his release from British custody, Mende took up the study of law and political science at Cologne University, gaining his doctorate in 1949.
He also helped to found the Free Democratic Party (FDP) in 1945.

His party was the most freemarket-orientated of the three main German parties.
Mende was elected to the Bundestag in 1949 and rose swiftly through the ranks of his party.
By 1960 he was national chairman of FDP.
He held this post until 1968.

As a member of parliament Mende worked tirelessly on behalf of former soldiers, those who were released after lengthy captivity (the so-called Spatheimkehrer), and those condemned as war criminals.
He took a rather conservative, traditionalist view of how the new German armed forces, the Bundeswehr, should be structured and trained.

He was something of a thorn in Konrad Adenauer's side.
Adenauer's Christian Democrats were the main government party with which the FDP was in coalition.
After the FDP increased its vote in September 1961, in the wake of the building of the Berlin Wall in August 1961, Mende urged his party not to join Adenauer in another coalition.
The FDP did not take his advice.
He refused to take office, only changing his position once Ludwig Erhard had replaced Adenauer as Chancellor in 1963.

Under Erhard Mende served as Vice-Chancellor (deputy head of government) and Minister for All-German Affairs.
His task was to promote relations with Communist East Germany, the German Democratic Republic, not then recognised by the West Germans.
During his period of office West Berliners were permitted, for the first time, to cross the Wall for Christmas visits in December 1963.
From 1964, East German senior citizens were allowed to visit West Germany.

Mende inaugurated agreements on road building, especially on the autobahn near Hof to facilitate better communications with West Berlin.
Also during his time in office over 4,000 political prisoners held in East German prisons were "bought free" by West Germany.

The FDP lost office in 1966 with the fall of Erhard.
His successor at the head of the Christian Democrats, Kurt Georg Kiesinger, decided on a coalition with the main opposition party, the Social Democrats of Willy Brandt.
In opposition Mende turned his attention to his finances and worked as representative of the American international investment bank, IOS.
His party veered to the left and he was replaced in January 1968 by Walter Scheel.
He left the Bundestag in 1969.

In the following year the FDP became the junior partner in Brandt's SPD-FDP coalition.
In protest against Brandt's new Ostpolitik and the recognition of the Oder–Neisse line Mende left the FDP in 1970 and joined the Christian Democrats in opposition.
His defection did not have much impact on the coalition or his party's fortunes.
He served in the Bundestag again as a CDU Member from 1972 through 1980, but failed to make much impact in the ranks of the Christian Democrats.
On his release from British custody, Mende took up the study of law and political science at Cologne University, gaining his doctorate in 1949. He also helped to found the Free Democratic Party (FDP) in 1945.
His party was the most freemarket-orientated of the three main German parties. Mende was elected to the Bundestag in 1949 and rose swiftly through the ranks of his party. By 1960 he was national chairman of FDP. He held this post until 1968.
As a member of parliament Mende worked tirelessly on behalf of former soldiers, those who were released after lengthy captivity (the so-called Spatheimkehrer), and those condemned as war criminals. He took a rather conservative, traditionalist view of how the new German armed forces, the Bundeswehr, should be structured and trained.
He was something of a thorn in Konrad Adenauer's side. Adenauer's Christian Democrats were the main government party with which the FDP was in coalition. After the FDP increased its vote in September 1961, in the wake of the building of the Berlin Wall in August 1961, Mende urged his party not to join Adenauer in another coalition. The FDP did not take his advice. He refused to take office, only changing his position once Ludwig Erhard had replaced Adenauer as Chancellor in 1963.
Under Erhard Mende served as Vice-Chancellor (deputy head of government) and Minister for All-German Affairs. His task was to promote relations with Communist East Germany, the German Democratic Republic, not then recognised by the West Germans. During his period of office West Berliners were permitted, for the first time, to cross the Wall for Christmas visits in December 1963. From 1964, East German senior citizens were allowed to visit West Germany.
Mende inaugurated agreements on road building, especially on the autobahn near Hof to facilitate better communications with West Berlin. Also during his time in office over 4,000 political prisoners held in East German prisons were "bought free" by West Germany.
The FDP lost office in 1966 with the fall of Erhard. His successor at the head of the Christian Democrats, Kurt Georg Kiesinger, decided on a coalition with the main opposition party, the Social Democrats of Willy Brandt. In opposition Mende turned his attention to his finances and worked as representative of the American international investment bank, IOS. His party veered to the left and he was replaced in January 1968 by Walter Scheel. He left the Bundestag in 1969.
In the following year the FDP became the junior partner in Brandt's SPD-FDP coalition. In protest against Brandt's new Ostpolitik and the recognition of the Oder–Neisse line Mende left the FDP in 1970 and joined the Christian Democrats in opposition. His defection did not have much impact on the coalition or his party's fortunes. He served in the Bundestag again as a CDU Member from 1972 through 1980, but failed to make much impact in the ranks of the Christian Democrats.
Erich Mende