Lutosławski left Warsaw in July 1944 with his mother, merely a few days before the Warsaw Uprising, salvaging only a few scores and sketches; the rest of his music was lost during the complete destruction of the city by Germans after the fall of uprising, as were the family's Drozdowo estates. Of the 200 or so arrangements that Lutosławski and Panufnik had worked on for their piano duo, only Lutosławski's "Paganini Variations" survived. Lutosławski returned to the ruins of Warsaw after the Polish-Soviet treaty in April 1945.