James Conlon is a maestro on a mission. Over the past several years, the esteemed American conductor -- musical director of the Paris National Opera and director designee of Chicago's Ravinia Festival -- has embarked on a quest to perform the music of composers affected by the rise of Nazism in 1930s and '40s Europe. Because of this musical archaeologist's limitless energy, music once deemed "degenerate" and banned from performance is now filling the world's concert halls.

Last evening at the Kennedy Center, Conlon and the National Symphony Orchestra focused on music composed and performed at the Theresienstadt concentration camp in what was then western Czechoslovakia. At this "model" camp, the Nazis gave some creative freedoms to well-known artists and intellectuals with the idea of deceiving the world about their true intent.

Along with strong performances of works by well-known Czech composers, the NSO gave riveting accounts of the music of two of the camp's prominent Jewish-Czech composers, Viktor Ullmann and Pavel Haas. Both completed significant musical scores while incarcerated in the camp. In 1944, Ullmann and Haas were deported to Auschwitz and murdered on the same day.

With this horrific background in mind, one expected to hear suffused through the music gloomy, foreboding signs such as straining chords or dissonant passage. It was surprising then to hear Ullmann's Symphony No. 2, based on a piano sonata that he completed only months before his death. Through its lyricism and bustling rhythms, the work belies the horrifying circumstances in which the composer worked. In the first movement, the NSO gave a lilting, spacious feel to the contrasting themes. Although the adagio struck darker notes, the generally colorful sound never lingered too far beneath the surface, and there was an almost joyous quality to the playing at several points.

Haas's "Studies for String Orchestra" was a more introverted affair, including many rigorously constructed fugues and strongly contrasting sections. Still, the complex counterpoint came off more as the product of a strong musical mind seeking distraction than as a cry against the loss of freedom and hope. The NSO rendered this eight-minute work with special technique and musicality.

The superb 24-year-old violinist Sarah Chang joined the orchestra for a crisp rendition of Antonin Dvorak's Violin Concerto in A Minor, Op. 53, which was featured in some of the camp's concerts. Chang seems to have nicely weathered the sometimes tough transition from child prodigy to mature artist, and her playing was everywhere alive to the lyrical spirit of the score. It helped that she had collaborated before with Conlon and the NSO. As the movements unfolded, these musicians skillfully accentuated the conversational elements of the concerto with sizzling energy. The second movement adagio was meltingly beautiful.

While the Dvorak and three dances from Bedrich Smetana's "The Bartered Bride," which opened the concert, were lovely and enjoyable, the chance to hear the music of two highly creative yet cruelly extinguished composers was what made the concert well worth the time.

The program will be repeated tonight and tomorrow evening.

Maestro James Conlon has touted music created by the Nazis' victims.Violinist Sarah Chang brought out the lyrical spirit of the score.