Genscher fought as a young man in the Wehrmacht at the end of the Second World War. In 1945, Genscher was a young soldier in General Walther Wenck's 12th Army. He participated in Wenck's ill-fated relief effort during the Battle for Berlin which Hitler saw as a last roll of the dice to save the besieged city. While Wenck's attack was unable to relieve or save the city of Berlin, he was able link up with the remnants of Colonel General (Generaloberst) Theodor Busse's 9th Army. Together, they marched what was left of both armies, along with many civilians, to the American lines and surrendered. For this reason, Genscher briefly became an American and British prisoner of war. After World War II, he studied law and economics at the universities of Halle and Leipzig (1946-1949) and joined the East German Liberal Democratic Party (LDPD) in 1946.
Overcoming criticisms of his involvement with the Nazi Party at a young age, in 1965 at the age of 38, Genscher was elected to the West German parliament for the first time from Bremen, a seat he would hold until his retirement in 1998. After serving in several party offices, he was appointed Minister of the Interior by Chancellor Willy Brandt, whose Social Democratic Party was in coalition with the FDP, in 1969; in 1974, he became foreign minister and Vice Chancellor.
In 1972 while Minister for the Interior, he rejected Israel’s offer to send an Israeli special forces unit to Germany to deal with the Black September hijacking of the 1972 Summer Olympics which led to the Munich massacre. The German government said they could deal with it themselves. They were wrong and it ended in a bloody shootout at Fürstenfeldbruck Air Base which left 11 hostages, 5 terrorists, and 1 German policeman dead. Genscher's popularity with Israel declined further when he endorsed the handing over of the three captured hijackers to the Palesetinians following the hijacking of a Lufthansa plane on October 29 1972. This was widely believed to be a setup (German - Palestinian collusion) and led to further criticism of the German government for negotiating with hijackers. Around this time, German relations with Israel, already strained after the Holocaust deteroriated even further still.
In the SPD-FDP coalition, he helped shape Brandt's policy of deescalation with the communist East, commonly known as Ostpolitik, which was continued under Helmut Schmidt after Brandt's resignation in 1974.
Still, Genscher was one of the FDP's driving forces when, in 1982, the party switched sides from its coalition with the SPD to support the CDU/CSU in their Constructive Vote of No Confidence to have Helmut Schmidt replaced with Helmut Kohl as Chancellor. Despite the great controversy that accompanied this switch, he remained one of the most popular politicians in West Germany. He retained his posts as foreign minister and vice chancellor through German reunification and until 1992, when he stepped down for health reasons. Some believe his 18-year tenure as foreign minister made him the longest-serving holder of such an office anywhere in the world.
In 1991, Genscher raced to recognize the Republic of Croatia in the Croatian War of Independence shortly after the Serbian attack on Vukovar. The rest of the European Union was pressured to follow suit soon afterward. Historically Germany has had a close collaboration with Croatia. Germany was active in putting together the coalition against Slobodan Milosovic.
Genscher was also an active participant in the further development of the European Union, taking active part in the Single European Act Treaty negotiations in the mid 1980s, as well as the joint publication of the Genscher-Colombo plan with Italian Prime Minister Colombo which advocated further integration and deepening of relations in the European Union towards a more federalist European State.