In the summer of 1944, the Soviet Red Army reached eastern Lithuania. By July 1944, the area around Vilnius came under control of the Polish Resistance fighters of the Armia Krajowa, who also attempted a takeover of the German-held city during the ill-fated Operation Ostra Brama. The Red Army captured Vilnius with Polish help on 13 July. The Soviet Union re-occupied Lithuania and Joseph Stalin re-established the Lithuanian Soviet Socialist Republic in 1944 with its capital in Vilnius. The Soviets secured the passive agreement of the United States and Great Britain (see Yalta Conference and Potsdam Agreement) to this annexation. By January 1945, the Soviet forces captured Klaipėda on the Baltic coast. The heaviest physical losses in Lithuania during World War II were suffered in 1944–45, when the Red Army pushed out the Nazi invaders. It is estimated that Lithuania lost 780,000 people between 1940 and 1954 under the Nazi and Soviet occupations.