In December 1956, two months after the Hungarian revolution was violently suppressed by the Soviet Army, Ligeti fled to Vienna with his ex-wife Vera (whom he was soon to remarry) and eventually took Austrian citizenship in 1968.[6] He would not see Hungary again until he was invited to judge a competition in Budapest fourteen years later.[7] On his journey to Vienna, he left most of his Hungarian compositions in Budapest, some of which are now lost; he only took with him what he considered to be his most important pieces. He later explained, "I considered my old music of no interest. I believed in twelve-tone music!"[8]
A few weeks after arriving in Vienna he left for Cologne. There he met several key avant-garde figures and learned more contemporary musical styles and methods.[9] These included the composers Karlheinz Stockhausen and Gottfried Michael Koenig, both then working on groundbreaking electronic music. During the summer he attended the Internationale Ferienkurse für Neue Musik in Darmstadt. Ligeti worked in the Cologne Electronic Music Studio with Stockhausen and Koenig and was inspired by the sounds he heard there. However, he produced little electronic music of his own, instead concentrating on instrumental works which often contain electronic-sounding textures.
After about three years' working with them he finally fell out with the Cologne School, this being too dogmatic and involving much factional in-fighting: "there were [sic] a lot of political fighting because different people, like Stockhausen, like Kagel wanted to be first. And I, personally, have no ambition to be first or to be important."[2]
From about 1960 Ligeti's work became better-known and respected. His best-known work include works in the period from Apparitions (1958–59) to Lontano (1967) and his opera Le Grand Macabre (1978). In recent years his three books of Études for piano (1985–2001) have become better-known through recordings by Pierre-Laurent Aimard, Fredrik Ullén, and others.
In 1973 Ligeti became professor of composition at the Hamburg Hochschule für Musik und Theater, eventually retiring in 1989. In the early 1980s, he tried to find a new stylistic position (closer to "tonality"), leading to an absence from the musical scene for several years until he reappeared with the Trio for Violin, Horn and Piano (1982). His output was prolific through the 1980s and 1990s. Invited by Walter Fink, he was the first composer featured in the annual Komponistenporträt of the Rheingau Musik Festival in 1990.[citation needed]