Final answer:
During World War II, advancing Soviet armies began liberating death camps in July 1944, and by April 1945, U.S. and British units liberated camps such as Buchenwald, Bergen-Belsen, and Dachau.
Step-by-step explanation:
The question refers to the rescue of prisoners at concentration camps during World War II. Toward the end of the war, prisoners were liberated from these camps by the allies. According to historical records, advancing Soviet armies began the process of liberating the death camps in July 1944, with the liberation of Auschwitz occurring in January 1945. In April, U.S. and British units liberated camps like Buchenwald, Bergen-Belsen, and Dachau. These liberation efforts were a part of the allied offensives against Nazi Germany across Europe and were instrumental in ending the Holocaust and World War II in Europe.