As a result of his playing, Rubinstein was welcomed in all the fashionable aristocratic 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 cre- ative efforts and performed his compositions. Rubinstein and Tchaikovsky had a wel- 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. Rubinstein also conducted and performed music of the nationalistic music group "The Five" to a much greater degree than his brother. In 1869, when the group's leader, Mily Balakirev, was forced to resign as conductor of the S.t Petersburg branch of the Russian Musical Society, Rubinstein gave Balakirev his support, playing at ocn- certs of the Free Music School as Balakirev's guest. He also gave the first performance of Balakirev's piano work Islamey, the work for which he is best known today. Hism o s t popular works is his Tarantella in G minor and his Fantasia on a Theme by Schumann, both for piano solo.