Task: Question Answering
Input (English): Passage: With the outbreak of World War I on 28 July 1914, The Oceanides languished. Wartime politics being what they were, Sibelius's music was seldom played outside the Nordic countries and the United States: in Germany, there was little demand for the music of an "enemy national", while in Russia, Finns were viewed as being "less than loyal subjects of the Tsar". In any case, many of Sibelius's works had been printed by German publishing houses, a detail that harmed Sibelius's reputation not only in Russia, but also Britain and the United States. According to Tawaststjerna, the war plunged Sibelius into a state of melancholy and creative struggle (the Fifth and Sixth symphonies were in the process of simultaneous gestation at this time). His response was to retreat into near solitude: he abstained from attending and giving concerts and neglected his circle of friends, and he imagined himself "forgotten and ignored, a lonely beacon of light in a deepening winter darkness".Sibelius was not easily stirred from his exile; friend and fellow composer Wilhelm Stenhammar, then Artistic Director and chief conductor of the Gothenburg Symphony Orchestra, wrote to Sibelius repeatedly to persuade him to conduct a concert of his works in Gothenburg. Believing himself duty-bound to premiere a "major work" in Sweden, such as a symphony, Sibelius—to Stenhammar's chagrin—delayed each scheduled trip. He withdrew from planned concerts for March 1914, writing to Stenhammar, "My conscience forces me to this. But when I have some new works ready next year, as I hope, it would give me great joy to perform them in Gothenburg". New arrangements were made for February 1915, but these, too, Sibelius canceled in December 1914. In the end, the indefatigable Stenhammar prevailed and new concerts were set for March 1915 ("I see yet again your great sympathy for my music. I shall come".).Stenhammar's efforts were rewarded with the European premiere of The Oceanides. For Sibelius, it was an opportunity to once again be an "artist on tour", feeding off the energy and "rapturous ovations" of an audience (it had been nine months since the Norfolk concerts, which now seemed a distant memory). The first concert, on March 22, featured the Second Symphony, Scènes historiques II, and two movements from Swanwhite before concluding with The Oceanides. According to Sibelius's diary, the performance was a "great success", with Stenhammar "captivated" particularly by the final number. The 24 March program retained The Oceanides, but paired it with Scènes historiques I, the Nocturne from the King Christian II Suite, a movement from Rakastava, Lemminkäinen's Return, and the Fourth Symphony. Sibelius was very pleased with the orchestra's handling of The Oceanides, calling its performance "wonderful". He goes on to note in his diary that, "After the final number [The Oceanides] there was a deafening torrent of applause, stamps, cries of bravo, a standing ovation and fanfares from the orchestra". 
Question: What is the last name of the man that put on a performance that captivated the chief conductor of  the Gothenburg Symphony Orchestra?
Output (English): Sibelius.