The deadliest prisoner of war camp during the Civil War was Andersonville prison. Andersonville was run by the Confederate States Army. At Andersonville, about one quarter of the prisoners died.
Conditions at the Union's prisoner of war camps were also very bad. At four different Union camps, at least 15% of the prisoners in the camps died. At a camp called Fort Pulaski, Union soldiers starved 600 Confederate prisoners of war on purpose. 46 of them died. The Union soldiers did this to get revenge for how Union prisoners were treated at Andersonville Prison.
By the end of the Civil War, about 30,000 Union soldiers, and about 26,000 Confederate soldiers, had died in prisoner of war camps.
In the late 1800s, Cuba was a colony of the Spanish Empire. This meant Spain controlled Cuba. When Cuban people tried to rebel and fight for independence from 1895 to 1898, Spain created concentration camps and sent many Cuban people to live in them. This was called the "Reconcentrado" ("Reconcentration") Policy.
The people fighting for Cuban independence were guerrilla fighters. They did not wear military uniforms and could hide themselves in groups of civilians. They could also camp and hunt, without needing help from anybody to survive. To keep the guerrilla fighters from being able to do these things, the Spanish government decided to put Cuban people in concentration camps. The idea was that in the camps, Cuban people could be 'protected' by the Spanish Army until the Spanish Empire won the war. However, this idea did not work. At least 30% of the Cuban people in the camps died from hunger, disease, bad sanitation, and not having medicines. Also, the concentration camps did not help the Spanish win the war.
Between 1900 and 1902, the British Empire, led by Lord Kitchener, used concentration camps. At the time, they were fighting the Boer people in the Second Boer War in South Africa. At first, the British were not able to beat the Boers. They reacted by putting the Boer fighters' family members into concentration camps. They did this so these family members could not give food or help to the Boer fighters. The British soldiers also burned down the Boers' houses and farms, and destroyed all the crops they could find. They did this so the Boer fighters would not be able to find food or shelter anywhere.
Russia used prison camps, especially in places in the Arctic or Siberia, a long way from the main cities. The first prison camp in Russia was built in 1918. However, after the Soviet Union was formed in the 1922, the Soviet government started sending many more people to forced labor camps. By 1936, there were 5,000,000 inmates in these camps.
These camps are called "zone" in Russian. They are also commonly called "gulags". GULAG is an acronym for the Russian words "Main Camp Administration" (ru: Главное управление лагерей и мест заключения; Glavnoe upravlenye lagerey i mest zaklyucheniya). This was the government agency that was in charge of the prison camps while Josef Stalin led the Soviet Union. However, people who do not speak Russian often use the word "gulag" to talk about any forced labor camp in Russia or the Soviet Union.
People sent to the gulags included:
During World War II, Nazi Germany created many concentration camps, slave labor camps, and extermination camps (death camps). Nazi Germany's leader, Adolf Hitler, thought that certain groups of people were inferior (not as good as others). He even thought there were groups of people who did not deserve to live - he called them "life unworthy of life." These three groups were Jews, Roma people, and people with disabilities. Hitler wanted his Nazis to kill every Jew, Roma, and disabled person in Europe.
Hitler also wanted to get rid of other groups he did not like, including people who he thought might challenge or fight the Nazi government. These people included socialists, communists, people of certain religions, and members of resistance movements (groups who tried to fight the Nazis any way they could).
The Nazis sent many of these people to concentration camps to work as slave labor. After a few years, some camps were set up just to kill people. These are now called "extermination camps" or "death camps." At these camps, people were killed in gas chambers, shot, worked to death, and marched to death. Many people also died from disease and starvation in the camps.
More than half of the Jewish people who died in the Holocaust died at Nazi concentration camps. Just in the Auschwitz camps, at least 1.1 million people died (about 1,000,000 Jews and about 75,000 non-Jewish people, like Poles). Towards the end of World War II, the Nazis killed up to 20,000 people a day in the camps' gas chambers.
With Nazi Germany's support, the Ustaše government of the new Independent State of Croatia (ISC) created concentration camps and extermination camps. Mainly, the camps were for Serbs. The ISC hated Serbs and thought of them as the ISC's biggest enemy. However, the Ustaše also helped the Nazis with the "Final Solution" by killing many Jews in these camps. Other people the Ustaše forced into the camps included Roma, Croats, Yugoslavians who had fought against the ISC, and people who broke rules and laws set by the ISC.
During World War II, the United States forced over 110,000 Japanese-Americans into internment camps.
On December 7, 1941, Japan attacked Pearl Harbor, Hawaii. In February 1942, the United States government ordered that nobody with Japanese ancestry could live on the West Coast. The government, led by President Franklin Delano Roosevelt, thought that Japanese-American people might be spies for Japan, or might try to hurt the United States.
About 80% of the Japanese-American people who lived in the continental United States were forced to leave their homes and live in internment camps. More than three out of every five of these people were born in the United States, and were United States citizens. About half of the people sent to the camps were children.
After Canada declared war on Japan, it also forced people with Japanese ancestry into internment camps.
In the 1980s, the United States government admitted that Japanese-Americans were not a danger to the country during World War II. In 1988, President Ronald Reagan signed a law that apologized for the internment camps. The law said "there was no ... reason for the internment ... [and] the internment was caused by racial prejudice, war hysteria, and a failure of [government] leadership[.]"
During World War II, Italy's fascist government (led by Benito Mussolini) was Nazi Germany's ally. Italy had taken over Yugoslavia, Greece, and the southeast part of France. The Nazis told Italy to put Jews from these areas in concentration camps and then send them to the Nazis' death camps. However, Italy refused. The Italian military and police would not help kill or deport Jews.
However, in 1943, after Mussolini had lost power, Nazi Germany took over northern and central Italy. They also put Mussolini back in power. The Nazis created concentration camps to hold Italian Jews and other prisoners until they could be sent to death camps. In one of these concentration camps, called La Risiera di San Sabba, the Nazis tortured and murdered about 5,000 people. Many of these people were "political prisoners" - people who disagreed with the government.
The number of Nazi German occupation government's prison camps, were "around 500" or 709 including some death camps.
When Josef Stalin and the Soviet Union invaded Poland at the start of World War II, the Red Army deported at least 1.5 million Poles at gunpoint. They were forced to get into cattle wagons (train cars), which took them to Siberia. Whole families were deported to concentration camps, including children and the elderly.
During the war, the Soviet Union also used gulags to hold prisoners of war from Nazi Germany and its allies.