As a result of his playing, Rubinstein was welcomed in all the fashionable artistocratic houses in Moscow. He co-founded the Moscow branch of the Russian Musical Society in 1859 and the Moscow Conservatory in 1866 with Prince Nikolai Petrovitch Troubetzkoy, serving as director of the latter until his death in 1881. He hired Tchaikovsky, then newly graduated from the Saint Petersburg Conservatory, to teach harmony at Moscow Conservatory. He actively encouraged Tchaikovsky's creative efforts and performed his compositions. Rubinstein and Tchaikovsky had a well-known falling-out over the latter's First Piano Concerto, but Rubinstein later revised his position and became an ardent champion of the work. Rubinstein conducted the premiere of Tchaikovsky's opera "Eugene Onegin" in 1879. Tchaikovsky wrote his Piano Trio in A minor in Rubinstein's memory after he died from tuberculosis in Paris.