21 Deadliest Wars And Other Horrific Events In History Of Mankind

Take a historical and educational look at the past and see what we can learn about the deadliest wars and other horrific events.

You might be a little confused reading the title, so we will begin by telling you that we are talking about human deprivation on a mass scale. What events in human history have led to the most deaths.

We are using a list that was created by author Matthew White, who describes himself as an “atrocitologist.” He writes about what he calls “Hemoclysms”, or blood floods. White studied as many documents as he could and put together a list of the deadliest wars and other horrific events and what or who was to blame.

If many millions died due to some conflict in the 8th century, when the world population was around 220 million (according to Worldometers) that could be considered worse than many millions, perhaps many more millions, dying when the world had a population of say 2 billion. We will give you the biggest death tolls in history, but also tell you what were perhaps the biggest blood floods in terms of the population when the deaths happened.


We should add the disclaimer that these figures are in no way totally accurate, even when we speak about tragedies of the 20th century. They are estimates, and the further we go back the more guesswork is employed.

Getting our hands on accurate historical data from hundreds of years ago is not possible, so scientists just do their best. In terms of conflicts, we are talking about soldiers and civilians as well as corollary casualties such as those that died from famine during conflicts.

As Pinker points out, this is also tricky, because we must ask how many people would have died from famine during those years if a conflict had not occurred. Anyway, here’s the list, from worst to absolute worst.


21. French Wars of Religion (16th century – 3 million deaths)

St. Bartholomew’s Day massacre, by François Dubois, Public domain, via Wikimedia Commons

French Wars of Religion spanned from 1562 to 1598 and were over the matter of religion, in this case, Catholicism and Reformed/Calvinist Protestants. We use the plural because there were eight wars in total. As you likely know there was a Protestant Reformation going on in Europe, and this shift in religious ideas was hard to stomach for Catholics.

This might seem a paltry matter today, but it certainly wasn’t then. After all the deaths from massacres, fighting, famine and disease it was agreed upon to promote civil tolerance and religious coexistence.

Mid-20th Century adjusted death toll: 14 million deaths (17th place)


20. Chinese Civil War (20th century – 3 million deaths)

Clockwise from the top: communist troops at the Battle of Siping; Muslim soldiers of the NRA; Mao Zedong in the 1930s; Chiang Kai-shek inspecting soldiers; CCP general Su Yu inspecting the troops shortly before the Menglianggu campaign, by Makakaaaa, Public Domain, via Wikimedia Commons

This lasted from 1927 to 1936 and was fought between the Communist Party of China and the Republic of China. Many, many battles would be fought, with another civil war following.

Mid-20th Century adjusted death toll: 3 million deaths (21st place)

19. Napoleonic Wars (19th century – 3 million deaths)

Battle of Austerlitz, 1805, by François Gérard, Public domain, via Wikimedia Commons

For 12 years in the early 19th century, Napoléon Bonaparte led his troops to battle all over Europe. Many countries formed a coalition to fight against the little man and his armies, but the biggest foe was Great Britain. The wars ended when Napoleon was defeated on 18 June 1815 at the Battle of Waterloo (that’s in present day Belgium).


Two days prior, Napoleon’s army had defeated the Prussian army, but then they joined with a much larger British army led by the Duke of Wellington. That ended badly for Napoleon.

Mid-20th Century adjusted death toll: 11 million deaths (19th place)

18. Russia’s Time of Troubles (16-17th century – 5 million deaths)

Konstantin Makovsky’s Appeal of Minin (1896) depicts Kuzma Minin against the background of the church of St. John the Baptist appealing to the people of Nizhny Novgorod to raise a militia against the Polish invaders and Sigismund III Vasa, by Konstantin Makovsky, Public domain, via Wikimedia Commons

It sounds kind of vague, a time of troubles, but that’s what it was, many troubles. During this period Russia fought with the Polish, was occupied, saw multiple civil uprisings and experienced a terrible famine that wiped out much of the population.


Mid-20th Century adjusted death toll: 23 million deaths (14th place)

17. Thirty Years War (17th century – 7 million deaths)

Les Grandes Misères de la guerre (The Great Miseries of War) by Jacques Callot, 1632, by Jacques Callot, Public domain, via Wikimedia Commons

Thirty Years War was the worst of the religious wars, this was fought mainly in Central Europe and again it was related to the Protestant Reformation. The battles were fought from 1618 to 1648, but again, many of the deaths were related to famine, not just fighting.

Towns and villages were destroyed, and people all around Europe lost all they had. Armies marauded and disease and famine finished those left behind. Interrogations and witch hunts took many more lives. This was a time of brutality and paranoia all over Europe. People starved to death in the worst areas, and there were even reports of people resorting to cannibalism. A low point for Europe, and for religion, too.


Mid-20th Century adjusted death toll: 32 million deaths (13th place)

16. Congo Free State (19-20th century – 8 million deaths)

Photograph of King Leopold II of Belgium, Public Domain, via Wikimedia Commons

Led by the ruthless King Leopold II of Belgium, this part of Africa was plundered of its natural resources while the local people were carved up and brutalized in ways that turn one’s stomach.

This really was The Heart of Darkness, and it’s said that the Belgians decimated the population, with about 50 percent killed or dying because of the way they were worked. The horror, and we repeat, the horror, lasted from 1885 to 1908.


Mid-20th Century adjusted death toll: 12 million deaths (18th place)

15. Fall of Rome (3rd to 5th century – 8 million deaths)

Roman Republic Empire map – Roman Republic (RED), Roman Empire (PURPLE), Eastern Roman/Byzantine Empire (YELLOW), Western Roman Empire (BLUE), by Roke, licensed under CC BY-SA 3.0 via Wikimedia Commons

We bet you weren’t expecting this to be the on the list. The fall of Rome was a long, drawn-out affair, and it was a bloody spectacle, too. Civil wars, barbarian invasions, political crises, corruption, religious discord and God knows how many battles, and well, that led to a lot of blood flowing.

Mid-20th Century adjusted death toll: 105 million deaths (5th place)


14. Russian Civil War (20th century – 9 million deaths)

Clockwise from top left: Soldiers of the Don Army; Soldiers of the Siberian Army; Suppression of the Kronstadt rebellion; American troops in Vladivostok during the intervention; Victims of the Red Terror in Crimea; Hanging of workers in Yekaterinoslav by the Austrians; A review of Red Army troops in Moscow, by CapLiber, licensed under CC BY-SA 4.0 via Wikimedia Commons

Russian Civil War lasted from 1918 to 1921 and it was fought between what were called the Whites and the Reds, or you might just call them the Bolsheviks and the monarchists, capitalists and militarists or anyone else against Lenin’s ideology. The Socialists won and the Soviet Union soon was born. Some put the death toll much higher than 9 million because so many civilians died.

Mid-20th Century adjusted death toll: 9 million deaths (20th place)

13. First World War (20th century – 15 million deaths)

Clockwise from the top: The road to Bapaume in the aftermath of the Battle of the Somme, 1916; British Mark V tanks crossing the Hindenburg Line, 1918; HMS Irresistible sinking after hitting a mine in the Dardanelles, 1915; A British Vickers machine gun crew wearing gas masks during the Battle of the Somme, 1916; German Albatros D.III biplane fighters near Douai, France, 1917, by Hohum, Public domain, via Wikimedia Commons

We probably don’t need to tell you much about WWI. Tension was rife in Europe, Germany wanted an empire, and then a young man called Gavrilo Princip went and killed the Archduke Franz Ferdinand of Austria (that almost didn’t happen). 32 countries ended-up fighting and more civilians died than soldiers. The war started in 1914 and ended in 1918.


Mid-20th Century adjusted death toll: 15 million deaths (16th place)

12. British India – mostly preventable famine (19th century – 17 million deaths)

The British Indian Empire and surrounding countries in 1909, by Imperial Gazetteer of India / John G. Bartholomew, Public domain, via Wikimedia Commons

You can read many books about the impact the British had on India, with most historians taking a very dim view of what happened during the days of empire. Perhaps some writers, such as Niall Ferguson, believe the British did as much good as bad.

No one doubts that the British Empire was mostly responsible for some famines, knowing landlords were stockpiling food and charging high prices during times of crisis. British administrative policies were bad, taxes were raised, and while the Brits were exporting crops and making a ton of money, Indian peasants had nothing to eat. It’s a long complicated story and we can’t cover it all here.


Mid-20th Century adjusted death toll: 35 million deaths (12th place)

11. Timur Lenk – Tamerlame (14th-15th century – 17 million deaths)

Timur. Forensic facial reconstruction by M.Gerasimov. 1941, by shakko, licensed under CC BY-SA 3.0 via Wikimedia Commons

This Turco-Mongol conqueror travelled around parts of Asia, Africa, and Europe and his armies were feared like no other. He came, he saw, he conquered, and he left a trail of blood behind him, becoming a very powerful Muslim leader.

He was born in present day Uzbekistan. History tells us he had aspirations of another great Mongol Empire. This great military leader it seems died from something like a cold while he was on his way to cause mayhem in China.


Mid-20th Century adjusted death toll: 100 million deaths (6th place)

10. Atlantic Slave Trade (15th to 19th century – 18 million deaths)

The Slave Trade, by François-Auguste Biard, Public domain, via Wikimedia Commons

Another blight on humanity was the human trafficking of African people to be used, and abused, as slaves. There are many guilty parties from all parts of the world, but at this time it was mainly the European colonists that were the big slave-trading nations.

The slaves were worked, sometimes to death, in cotton plantations, mines, sugar plantations, or as construction workers, and more. Moreover, Muslim countries had been trading in African slaves before the Europeans.


In the USA the use of slaves split much of the country, and that was the main reason behind the American Civil War. The rich farmers in the south didn’t want the north’s anti-slavery sentiments forced on them, for fear of losing their free labor pool.

Mid-20th Century adjusted death toll: 83 million deaths (8th place)

9. Mideast Slave Trade (7th – 19th century – 19 million deaths)

A slave market in Cairo, by David Roberts, Public domain, via Wikimedia Commons

As we said, the slave trade had been going on in the Middle East long before the Europeans had blood on their rapacious hands. We should add that some Africans were absolutely involved in this trade, too, as sellers.


Mid-20th Century adjusted death toll: 132 million deaths (3rd place)

8. Josef Stalin (20th century – 20 million deaths)

Joseph Stalin in 1920, by Public Domain via Wikimedia Commons

We don’t need to tell you much about the paranoid so-called Man of Steel. His Great Purge sent many to the gulags, his policies led to mass starvation, and no one felt safe – not even those close to him.

Mid-20th Century adjusted death toll: 20 million deaths (15th place)


7. Annihilation of the American Indians (15-19th century – 20 million deaths)

U.S. Cavalry pursuing American Indians in 1876, by The United States Army and Navy, Public domain, via Wikimedia Commons

Almost overlooked by some Americans is how much blood was shed when settlers went over to the New World and exterminated anyone that stood in their way. The new Americans kept this going for centuries.

They destroyed people and slowly denuded a culture that had been there before them for a long time. While memes today surface on the Internet concerning the original immigrants in America (present Americans), the mass slaughter of indigenous people still remains somewhat a cloaked tragedy.

Mid-20th Century adjusted death toll: 92 million deaths (7th place)


6. Taiping Rebellion (19th century 20 million deaths)

Painting of the Battle of Anqing (1861), by Wu Youru, Public domain, via Wikimedia Commons

Taiping Rebellion took place from 1850 to 1864 when there was a revolt in China against the Ch’ing dynasty. Hung Hsiu-ch’üan, the leader of the rebellion, had ideas for a new dynasty called the Taiping (The New Peace). Influenced by Protestantism, he had many people behind him.

The poor were sick and tired of the abuses they suffered at the hands of the ruling Chinese, and they fought for change. The Brits ended up helping the Ch’ing dynasty when it looked like the Taipings were doing well.

This wasn’t out of concern for any Chinese people, but because the British feared their trade would suffer. The rebellion crashed and burned in the end.


Mid-20th Century adjusted death toll: 40 million deaths (10th place)

5. Fall of the Ming Dynasty (17th century – 25 million deaths)

Decisive Battle of Shanhai Pass leading Ming Dynasty to fall in 1644, Public Domain, via Wikimedia Commons

Still with China, for decades the Qing dynasty fought with the southern Ming dynasty. The Ming were also fighting their own peasants, many of whom had revolted. It took a long time, but the Qings were victorious.

Mid-20th Century adjusted death toll: 112 million deaths (4th place)


4. An Lushan Revolt (8th century – 36 million deaths)

Map of An Lushan Rebellion, by SY, licensed under CC BY-SA 4.0 via Wikimedia Commons

You’re probably wondering what this was, and you won’t be alone. It was another rebellion in China. It started in 755 and ended in 763. In short, the ruling Tang Dynasty came up against General An Lushan and his army, who wanted to form a new Great Yan dynasty with him as emperor. He was successful only for his own dynasty to later crumble.

He was even killed by his own son. Considering in that century there were about 220 million people in the world, well, imagine a war now killing around one-sixth of the world’s population.

Mid-20th Century adjusted death toll: 429 million deaths (1st place)


3. Mongol Conquests (13th century – 40 million deaths)

Map showing growth of the Mongol Empire, by Astrokey44, licensed under CC BY-SA 3.0 via Wikimedia Commons

You’ve all heard about the Mongol Conquests first led by the great and brutal military leader, Genghis Khan, so we won’t go into details. The Mongol armies defeated armies all over Asia, the Middle East and parts of Europe.

Mid-20th Century adjusted death toll: 278 million deaths (2nd place)

2. Mao Zedong – mostly government caused famine (20 century – 40 million deaths)

Mao in 1959, by неизвестный, Public domain, via Wikimedia Commons

No fan of petty-bourgeois individualism, Mao Zedong set out to collectivize his people, and that was tragic in many ways. His brutal campaign led to the deaths of millions, and his great leap forward was a terrible fall backwards for much of the country.


His policies led to starvation from famine. His punishments were harsh, people were sent to camps to slowly die, and some deliberately starved to death. Historians tell us the atrocities at the very worst included parents being forced to bury their own children alive if they had transgressed.

Mid-20th Century adjusted death toll: 40 million deaths (11th place)

1. Second World War (20th century – 55 million deaths)

Clockwise from the top-left: Battle of Wanjialing; First Battle of El Alamein; Battle of Stalingrad over Eastern Front winter 1943-1944; Wilhelm Keitel signing German Instrument of Surrender; Invasion of Lingayen Gulf, by Staberinde, licensed under CC BY-SA 3.0 via Wikimedia Commons

Again, we don’t need to explain to you what happened here. World War II spanned the globe from 1939 to 1945. The numbers vary drastically as to how many died in total, with civilian casualties hard to know. War-related disease and famine took many millions of lives, as did the battlefield.


Mid-20th Century adjusted death toll: 55 million deaths (9th place)

Oscar Wilde once said, “As long as war is regarded as wicked, it will always have its fascination. When it is looked upon as vulgar, it will cease to be popular.

We are now perhaps at a stage when we see such brutality as vulgar, even though we still sometimes prefer heroism over actual honestly depicted brutality. We can tend to gloss over historical tragedy, which might be a grave mistake.


We have, however, experienced a “Long Peace” in terms of big wars, and some believe, or hope, we might be past mass murder such as we have discussed in this show. We might also have evolved out of treating other human beings like products, and doing away with them as we choose.

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