In July 1913, Max Planck and Walther Nernst asked Einstein to come to Berlin, which he agreed to, but the decision caused Marić distress. In August the Einsteins planned a walking holiday with their sons and Marie Curie and her two daughters. Marić was delayed temporarily due to Eduard being ill, but then joined the party. In September 1913, the Einsteins visited Marić's parents near Novi Sad, and on the day they were to leave for Vienna, Marić had her sons baptised as Orthodox Christians. After Vienna, Einstein visited relatives in Germany while Marić returned to Zurich. After Christmas, she traveled to Berlin to stay with Fritz Haber, who helped her look for accommodation for the Einsteins' impending move in April 1914. The Einsteins both left Zurich for Berlin in late March. On the way, Einstein visited an uncle in Antwerp and then Ehrenfest and Lorentz in Leiden, while Marić took a swimming holiday with the children in Locarno, arriving in Berlin in mid-April.