The prisoner enclosure at the camp was heavily guarded to ensure that no prisoners escaped. A 3-metre-wide (10 ft) no-man's land was the first marker of confinement for prisoners; an area which upon entry would elicit lethal gunfire from guard towers. Guards are known to have tossed inmates' caps into this area, resulting in the death of the prisoners when they attempted to retrieve the caps. Despondent prisoners committed suicide by entering the zone. A four-foot-deep and eight-foot-broad (1.2 × 2.4 m) creek, connected with the river Amper, lay on the west side between the "neutral-zone" and the electrically charged, and barbed wire fence which surrounded the entire prisoner enclosure.
Once Germany took over Poland in 1939, it created forced-labor camps. Thousands of prisoners died from working conditions, exhaustion, and starvation. After the outbreak of World War II, the number of concentration camps increased exponentially. The number of prisoners of war camps also rose, but after the first years of the war most were converted into concentration camps. Nazis forcibly relocated Jews from ghettos to concentration camps.
The camp was liberated on April 15, 1945, by the British 11th Armoured Division. The soldiers discovered approximately 60,000 prisoners inside, most of them half-starved and seriously ill, and another 13,000 corpses, including those of Anne and Margot Frank, lying around the camp unburied. The horrors of the camp, documented on film and in pictures, made the name "Belsen" emblematic of Nazi crimes in general for public opinion in many countries in the immediate post-1945 period. Today, there is a memorial with an exhibition hall at the site.