The German population east of Oder-Neisse was estimated at over 11 million in early 1945.[3] The first mass flight of Germans followed the Red Army's advance and was composed of both spontaneous flight driven by rumours of Soviet atrocities, and organised evacuation starting in the summer of 1944 and continuing through to the spring of 1945.[4] Overall about 1% (100,000) of the German civilian population east of the Oder–Neisse line perished in the fighting prior to the surrender in May 1945.[5] In 1945, the eastern territories of Germany as well as Polish areas annexed by Germany were occupied by the Soviet Red Army and Polish Communist military forces.