Kajanus had a decisive impact upon the development of the career of Jean Sibelius. He was considered an authority on the interpretation of Sibelius's music, and he and Sibelius were close friends; but this was compromised in 1898 when Sibelius was appointed to a university post for which Kajanus was himself a candidate. Kajanus appealed, and the decision was overturned. But they reconciled for the orchestra's tour of Europe in 1900, where they appeared at the Exposition Universelle at the invitation of the French government. "Kullervo", Sibelius's epic masterpiece, was written in the wake of Kajanus' symphonic poem "Aino" although Sibelius denied any exertion of influence of this piece over his own work. Additionally, as a conductor, Kajanus was responsible for commissioning one of Sibelius' most popular and enduring works, "En Saga", following the success of "Kullervo". "Pohjola's Daughter" was dedicated to Kajanus. When Kajanus took the Helsinki Orchestra on a tour of Europe in 1900 both he and Sibelius conducted, including what proved to be the first performances of Sibelius's music outside of Finland. This ensured the spread of the young composer's reputation far beyond the borders of his homeland, the first Finnish composer to receive such attention.