The Deadliest Wars and Crimes Against Humanity in History

War, terrorism, and crimes against humanity are stains that mar our collective history. This infographic from the Parker Waichman team delves into the deadliest wars and conquests, the deadliest terrorist attacks, the deadliest genocides, the political leaders with the most victims, the deadliest periods of slave trade and forced labor, and the deadliest aerial bombings. It’s important to be informed of these human-committed horrors and the events leading up to them so that we can be compassionate, respectful, and aware.

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What Are the Deadliest Wars of All Time?

The deadliest war in history was World War II. While it’s impossible to pinpoint the exact number of World War II casualties, historians have estimated a total of 70 to 85 million people. To put that into perspective, 3% of the world’s population perished during this colossal and devastating war with the most casualties. Deaths directly caused by the war were estimated to be around 50 to 56 million, with an additional 19 to 28 million deaths caused by disease and famine related to the war. Among the other wars and conquests with the highest death tolls are the Mongol conquests of the 13th and 14th centuries, the Taiping Rebellion, and the European colonization of the Americas.

What Country Had the Most Deaths in World War II?

According to the National World War II Museum database, the Soviet Union had the most casualties during World War II, at a total of 24,000,000. Historians estimate that the Soviet Union lost 8,800,000 to 10,700,000 through military deaths, which means that the majority of casualties were civilians. Why did the USSR suffer the most casualties? Several factors contributed to the Soviet Union WWII death toll, but most say that poor leadership was the main culprit:

1. Joseph Stalin disregarded early warnings that the Germans might attack, leaving Germany’s invasion of the Soviet Union to be the largest surprise attack in military history. He accepted Hitler’s lies about the sudden heavy German presence at the Soviet border and ignored dozens of reports from Soviet spies that an invasion was imminent.
2. The Germans had the element of surprise and more advanced technology, but the Soviets had an immense supply of troops, causing a dragged-out war and a staggering death toll. Treacherous winter conditions exacerbated the situation.
3. Stalin issued Order No. 270, which proclaimed that any soldiers who surrendered or allowed themselves to be captured were deemed traitors and would be executed if they ever returned. This was compounded by Order No. 227, which ordered troops to kill their comrades if they behaved cowardly or tried to flee.

Many other countries suffered immense death tolls during the deadliest war in history. Here are the five countries that experienced the most World War II casualties:

1. Soviet Union World War II casualties: 24,00,000
2. China World War II casualties: 20,000,000
3. Germany World War II casualties: 6,600,000 to 8,800,000
4. Poland World War II casualties: 5,600,000
5. Dutch East Indies World War II casualties: 3,000,000 to 4,000,000

How Many People Died During the Holocaust?

It is estimated that around 6 million Jews and 11 million total victims were killed during the Holocaust. During the Holocaust, Nazi Germany persecuted and murdered European Jews, ethnic Poles, Soviet civilians and prisoners of war, the physically and mentally disabled, the Roma, political and religious dissidents, and homosexuals.

What Are the Deadliest Terrorist Attacks of All Time?

The deadliest terrorist attack of all time is the September 11 attacks in which 2,977 people died in 2001. The attack continues to have effects on survivors to this day—toxic dust released from the destruction has caused illnesses in more than 18,000 people to date.

Here are the five deadliest terrorist attacks of all time:

1. September 11 Attacks (9/11/2001): 2,977 casualties
2. Camp Speicher Massacre (6/12/2014): 1,566 casualties
3. Yazidi Communities Bombings (8/14/2007): 796 casualties
4. Massacre of Sri Lankan Police Officers (6/11/1990): 774 casualties
5. Christmas Massacre (12/24/2008 – 12/27/2008): 620 casualties