From 1904 until 1914, Sergei and Elisabeth Bortkiewicz lived in Berlin. Bortkiewicz started here his career as composer. The couple lived at the Steglitzerstrasse 31 in Berlin with their scottish sheep dog Bobi. Bortkiewicz gave his first piano recitals in Berlin, Leipzig, Munich and Vienna. His piano concerto opus 1 (destroyed) was premiered on April 2, 1906 in Berlin.
He became friends with the opera diva Emmy Destinn (1878-1930) and went on concert tours with her to all the larger cities of Germany. He also appeared in Russia, Paris and Italy. In Berlin he gave private lessons, except for one year when he was engaged as a teacher in the Klindworth-Scharwenka Conservatory, where he was to meet his lifelong friend, the Dutch pianist Hugo van Dalen (1888-1967). Hugo van Dalen was born on April 16, 1888 in Dordrecht. He was the son of Jan Leendert van Dalen, archivist of the city of Dordrecht. He received his first piano lessons from J. Gijs de Vries. At age of 14 he started to study at the Conservatory of Music in Amsterdam, where he was taught by Johan Wijsman (1872-1913), Anton Tierie (1870-1938), Bernard Zweers (1854-1924), Daniël de Lange (1841-1918), Jan Willem Kersbergen (1857-1937) en Julius Röntgen (1855-1932). After completion of his study in Amsterdam in 1907 Röntgen advised Van Dalen to continue his education with Ferruccio Busoni (1866-1924) in Berlin, which he did for a period of 7 years. Meanwhile he was appointed as a teacher at the Klindworth-Scharwenka Conservatory in Berlin, were he met Sergei Bortkiewicz. After returning to the Netherlands at the start of WWI Van Dalen was appointed as a teacher at the Royal Conservatory of Music in The Hague, where he remained until his retirement. In 1920 he won the first prize at the Concours des Virtuoses in Paris, playing Van Beethoven’s fifth piano concerto under the baton of Gabriel Pierné with the Orchestre Colonne.

Van Dalen owed his marriage with his wife Sophia Wilhelmina Alberdina Rijckholt to Bortkiewicz. In his Erinnerungen Bortkiewicz says: “My opus 15 ten études for piano had just appeared with the publisher D. Rahter, when in Berlin I got acquainted with my present dear friend, the Dutch pianist Hugo van Dalen. When Van Dalen returned to Berlin after a long absence, he introduced me to his young pretty wife and assured me that he owed his married happiness to me. Naturally, I agreed. He then told me that my concert étude opus 15 no. 8 in D flat major pleased a Dutch young woman so much, that se had herself introduced to the pianist in order to ask him about the piece and the composer. From this acquaintance came love, engagement and marriage. Yet more noteworthy is the fact that exactly the same story was told to me later in Vienna by my friend, mr. Ernst Horicky, […] who came to know his wife in the same way. This time he was the curious one. Since then I have named the piece in D flat major as the Betrothal étude, and look on myself as a matchmaker.”

A major musical event in this period was his piano concerto no. 1 opus 16. The first performance (Urauffführung) of this concerto was in Berlin on Monday 24 February 1913 by Hungarian pianist Emeric von Stefaniai (1885-1959) and the Blüthner Orchestra conducted by Edmund von Strauss (1869-1919). Hugo van Dalen gave the Dutch première of the piano concerto no 1 on Wednesday 10 Oktober 1917 in Groningen (The Netherlands) by the ‘Orkest der Harmonie van de N.V. Groninger Orkestvereeniging’ conducted by Kor Kuiler. The first performance of the piano concerto in the USA was on Saturday 13 February 1915 in Carnegie Hall in New York. Soloist was Margaret [Marguerite] Volavy (1886-1951). The orchestra was the Russian Symphony Society conducted by Modest Altschuler (1873-1963).