Seventy-five years ago this month, Auschwitz—the largest concentration camp operated by German Nazis during World War II (1939-1945)—was liberated. More than 1 million men, women, and children died there, most of them Jewish.

In the 1930s, Germany’s leader, Adolf Hitler, and his Nazi Party rose to power by tapping into prejudice against Jewish people and blaming them for the country’s problems. Once in power, Hitler stripped Germany’s Jewish citizens of their rights. During World War II, Nazi forces occupied nations across Europe and sent millions of Jewish people to concentration camps.

Auschwitz was the deadliest such camp. Most people sent there were killed upon arrival with poison gas. The rest were forced to do hard labor and often died of starvation or illness.

As forces fighting the Nazis neared Auschwitz in January 1945, the Nazis evacuated prisoners and destroyed evidence of their crimes.

Soldiers from the Soviet Union entered the camp on January 27, 1945, freeing the 7,000 remaining prisoners, including those pictured above.

Germany surrendered in May 1945. By then, the Nazis and their collaborators had murdered more than 6 million Jewish people. This is known as the Holocaust. They killed 5 million others too, including Polish, disabled, and gay people.

Max Eisen’s family was murdered at Auschwitz. Eisen, who survived the camp, educates people about its horrors—and what everyone today can learn from the Holocaust. One of the most important lessons, he says: “Beware of hatred.”