Ullmann's opera "The Emperor" may at first sight look like an attempt to artistically depict the main characteristics of Nazism, because formulation- are being used here that were coined by the leading Nazis at the very end of the war. The opera, however, never degenerates into a snapshot of this particular historical phase. It evokes the eternal danger of planetary tyranny The Emperor is - like a number of works of art created in Theresienstadt proof of the human mind's ability to remain free even under the conditions of perfect slavery. Thus, all the mind's capacities are concentrated into one focal point, and lasting values are created, while the artist is facing annihilation.
H.T. Mandl on Ullmann

Viktor Ullmann (1898) was born in the old Austro-Hungarian empire in the city of Teschen. Both his parents were respectable persons in society: his father was a prominent colonel, his mother was a daughter of a famous Viennese jurist.
After finishing elementary school, he and his mother move to Vienna in 1909, where he is to follow the Rasumofsky Gymnasium. Musically talented, he decides to study with Josef Polnauer one of the disciples of Arnold Schoenberg. As part of a school event he shows his talents on a concert, by directing music from Mozart and Strauss.
In 1916, he joins the army and is sent to the Italian front. Although being promoted after the war he's finally getting convinced of the absurdity of war.
After returning from the war he's pressured by his parents to study law at the Viennese university but during his study he also manages to follow several of Schoenberg's seminars. He finally flees in 1919, marries and goes to Prague to devote himself to music. Early 20s he's hired as a 'Kapellmeister' at the 'Neuen Deutschen Theatre' (nowadays the National Opera of Prague). He collaborates with Alexander von Zemlinsky by preparing productions for Schoenberg's 'Gurrelieder' (1921), studies with Heinrich-Jalowetz (a close friend of Schoenberg). Between 1919 and 1927 he composes several works like Symphonic Fantasy, the stage music of the Kreiderkreis (which inspired Bertolt Brecht) and the first version of Variations and fugue on a theme by Schoenberg.
In 1929 he becomes a member of the Anthroposophical Society and he quits composing literally. His wife and him are leaving for Stuttgart to start a bookstore specialized in anthroposophy.
With the rise of the Nazis he's forced to return to Prague in 1933. Immediately he takes courses with Alois Haba and Haba inspires him to devote himself to composing again. Twice he is awarded the HERTZKA prize, in 1934 (for Schönberg Variations) and in 1936 (for his opera 'Der Sturz des Antichrist'/The Fall of The Antichrist).
His last trip as a free man is in 1938: he visits England to see the performance of his 'String Quarter No.2'.
Around September of 1942, he is found by the Nazis, and transported to Theresienstadt. Here he continues (under abominable conditions) to write music, give concerts and especially: gives lessons on Schonberg and Mahler. Among the twenty-four works he writes in the ghetto, are pieces like "Der Kaiser von Atlantis" (The Emperor of Atlantis) and his last requiem 'Die Weise von Liebe und Tod des Cornets Christoph Rilke' ('The tale of the life and death of the Cornet Cristoph Rilke'). He also finishes a short intellectual testimony, Goethe and the Ghetto at the end of his internment in Theresienstadt essentially saying that the 'arts presented in the ghetto where the victory of form over matter'.
Before he's transported to Auschwitz he hands over several transcripts to one of his closests friend.
Ullmann was taken from Theresienstadt on October 16, 1944 and killed in Auschwitz October 18, 1944.
Source:
Biogaphy by J. van Vlasselaar