25 Deadliest Wars In Human History We Should Never Forget Happened

Posted by , Updated on June 23, 2024

Conflicts have always been a part of human history. The oldest known battle happened around 14,000 years ago at a Mesolithic cemetery called Site 117. Wars have spread across the globe, causing the deaths of hundreds of millions.

And though these devastating events are usually meant to be fought between nations’ armies, the violence often spills into the civilian realm resulting in the deaths of countless innocent lives (which is why the total numbers of war casualties are so large and heartbreaking).

Apart from direct battle results, the statistics from the deadliest wars in human history also include war-related deaths caused by side effects such as induced epidemics, diseases, famines, atrocities, genocides etc. In order to bring awareness as to the devastating impacts of wars, we have compiled a list ranking the 25 deadliest wars in human history.

No matter what caused the conflicts, one thing is for sure – these wars cannot be considered anything but absolutely horrifying human tragedies that should have never happened. Let’s hope that by remembering our past, we are not doomed to repeat it.



Biafran War (death toll: 1 million)

Biafran WarSource and image: en.wikipedia.org

Also known as the Nigerian Civil War, the Biafran War (July 1967 – January 1970) was a war fought to counter the secession of Biafra, a secessionist state in Nigeria.

The conflict resulted from political, economic, ethnic, cultural and religious tensions which preceded Britain’s formal decolonization of Nigeria from 1960 to 1963. Most of the people who lost their lives in the war died from starvation and various diseases.


Japanese Invasion of Korea (death toll: 1 million)

Japanese Invasion of KoreaSource and image: en.wikipedia.org

Fought between 1592 and 1598, the Japanese invasions of Korea comprised two separate yet linked operations: the initial invasion in 1592, and the second invasion in 1597 that followed after a brief truce.

The conflict ended in 1598 with the withdrawal of the Japanese forces, leaving about 1 million casualties on the Korean side (Japanese casualties are unknown).


Iran–Iraq War (death toll: 1 million)

Iran–Iraq WarSource and image: en.wikipedia.org

The Iran–Iraq War was an armed conflict between Iran and Iraq lasting from 1980 to 1988, making it the 20th century’s longest conventional war. The war began when Iraq invaded Iran via air and land on 22 September 1980 and it ended with a stalemate on 20 August 1988.

In terms of the tactics used, the conflict has been compared to World War I as it included large-scale trench warfare, manned machine-gun posts, bayonet charges, human wave attacks across a no man’s land and extensive use of chemical weapons.


Siege of Jerusalem (death toll: 1.1 million)

Siege of JerusalemSource and image: en.wikipedia.org

The oldest conflict on the list (it took place in 73 AD), the Siege of Jerusalem was the decisive event of the First Jewish–Roman War. The Roman army besieged and conquered the city of Jerusalem, which had been occupied by its Jewish defenders.

The siege ended with the sacking of the city and the destruction of its famous Second Temple. According to historian Josephus, 1.1 million civilians died during the siege, mainly as a result of violence and famine.


Korean War (death toll: 1.2 million)

Korean WarSource: en.wikipedia.org, image: commons.wikimedia.org

Fought from June 1950 to July 1953, the Korean War was a major armed conflict that started when North Korea invaded South Korea. The United Nations, with US as the principal force, came to the aid of South Korea while China and the Soviet Union supported North Korea.

The fighting ended after an armistice was signed. The agreement created the Korean Demilitarized Zone to separate the Koreas, and allowed the return of prisoners. However, no peace treaty has been signed and the two Koreas are technically still at war.


Mexican Revolution (death toll: 1 - 2 million)

Mexican RevolutionSource: en.wikipedia.org, image: commons.wikimedia.org

Lasting from 1910 to 1920, the Mexican Revolution was a major armed struggle that radically transformed Mexican culture and government. Out of the population of 15 million, the losses were high but numerical estimates vary greatly.

Perhaps 1.5 million people died in the revolt and nearly 200,000 refugees fled abroad. The Mexican Revolution is often categorized as the most important sociopolitical event in Mexico and one of the greatest upheavals of the 20th century.


Shaka´s Conquest (death toll: 2 million)

Shaka´s ConquestSource and image: en.wikipedia.org

Shaka´s Conquest is a term used for a series of massive and violent conquests in Southern Africa led by Skaha, a prominent monarch of the Zulu Kingdom. In the first half of the 19th century, Shaka was in charge of a large army that invaded and plundered a number of regions in Southern Africa.

The kingdom destroyed tribe after tribe in a deadly cycle of fight and conquest. It is estimated that up to 2 million tribal people fell victim to the ravaging spree.


Goguryeo–Sui War (death toll: 2 million)

Goguryeo–Sui WarSource and image: en.wikipedia.org

Another violent conflict declared on Korea, the Goguryeo–Sui War was a series of campaigns launched by the Sui dynasty of China against Goguryeo, one of the Three Kingdoms of Korea, between AD 598 and AD 614.

The war (that was eventually won by the Koreans) caused death of 2 million people but the total death toll was probably much higher as the number does not include Korean and civilian casualties.


French Wars of Religion (death toll: 2 – 4 million)

French Wars of ReligionSource and image: en.wikipedia.org

Also known as the Huguenot Wars, the French Wars of Religion (fought between 1562 and 1598) is the name of a period of civil infighting and military operations, primarily fought between French Catholics and Protestants (Huguenots).

The exact number of wars and their respective dates are still debated by historians but it is estimated that up to 4 million people died as a result of the war, famine and war-related diseases.


Second Congo War (death toll: 2.5 – 5.4 million)

Second Congo War Source and image: en.wikipedia.org

Also known by several other names such as the Great War of Africa or the African World War, the Second Congo War is the deadliest war in modern African history. The war directly involved nine African countries, as well as approximately 20 separate armed groups.

The war was fought just for five years (from 1998 to 2003) but it caused up to 5.4 million deaths, principally through disease and starvation, making it the deadliest conflict worldwide since the World War II.


Napoleonic Wars (death toll: 3.5 – 6 million)

Napoleonic WarsSource and image: en.wikipedia.org

Fought between 1803 and 1815, the Napoleonic Wars were a series of major conflicts pitting the French Empire, led by Napoleon Bonaparte, a French military and political leader, against an array of European powers formed into various coalitions.  In his military career, Napoleon fought about 60 battles and lost just seven, mostly at the end of his reign.

The European total of the wars may have reached as many as 5 million military deaths, including diseases. There really is nothing good about war. Not only do they destroy the lives of Millions of people, but they also cost a considerable amount of money. Check out the most expensive wars ever fought here.


Thirty Years´ War (death toll: 3 – 11.5 million)

Thirty Years´ WarSource and image: en.wikipedia.org

Fought between 1618 and 1648, the Thirty Years’ War was a series of wars in Central Europe. One of the longest and most destructive conflicts in European history, the war initially began as a conflict between Protestant and Catholic states.

It began in the fragmented Holy Roman Empire but gradually developed into a much larger conflict involving most of the great powers of Europe. The death toll estimates differ significantly but the most probable count suggests that about 8 million people including civilians died in the war.


Chinese Civil War (death toll: 8 million)

Chinese Civil WarSource and image: en.wikipedia.org

The Chinese Civil War was fought between forces loyal to the Kuomintang (a political party of the Republic of China) and forces loyal to the Communist Party of China. The war began in 1927 and it essentially ended when major active battles ceased in 1950.

The conflict eventually resulted in two de facto states, the Republic of China (now known as Taiwan) and the People’s Republic of China in mainland China. During the war, both sides carried out mass atrocities, with millions of non-combatants deliberately killed.


Russian Civil War (death toll: 7 - 12 million)

Russian Civil WarSource and image: en.wikipedia.org

Fought between 1917 and 1922, the Russian Civil War was a multi-party war in the former Russian Empire that followed the Russian Revolutions of 1917 as many factions competed for power.

The two largest combatant groups were the Bolsheviks´ Red Army and the loosely allied forces known as the White Army. There were an estimated 7 – 12 million casualties during the war, mostly civilians. The Russian Civil War has even been described as the greatest national catastrophe Europe has ever seen.


Conquests of Tamerlane (death toll: 8 – 20 million)

Conquests of TamerlaneSource: en.wikipedia.org, image: commons.wikimedia.org

Also known as Timur, Tamerlane was a Turco-Mongol conqueror and a military leader. In the second half of the 14th century, he led brutal military campaigns across Western, South and Central Asia, Caucasus and southern Russia.

He emerged as the most powerful ruler in the Muslim world after defeating the Mamluks of Egypt and Syria, the emerging Ottoman Empire and the declining Delhi Sultanate. Scholars estimate that his military campaigns caused the deaths of 17 million people, which was about 5% of then world population.


Dungan Revolt (death toll: 8 – 20.8 million)

Dungan RevoltSource and image: en.wikipedia.org

The Dungan Revolt was a mainly ethnic and religious war fought between the Hans (Chinese ethnic group native to East Asia) and the Huis (Chinese Muslims) in 19th-century China.

The revolt arose over a pricing dispute involving bamboo poles. When a Han merchant selling to a Hui did not receive the amount demanded for the goods. Over 20 million people died in the revolt – mainly due to natural disasters and conditions brought on by the war such as drought and famine.


Conquest of the Americas (death toll: 8.4 – 138 million)

Conquest of AmericasSource: en.wikipedia.org, image: youtube.com

European colonization of Americas technically began as early as in the 10th century when West Norse sailors briefly settled areas on the shores of modern Canada but generally, the period between 1492 and 1691 is used when referring to the conquest of Americas.

During those 200 years, tens of millions people were killed in the battles between the colonizing powers and the native Americans but the total death toll estimates vary greatly due to lack of consensus as to the demographic size of the native population pre-Columbus.


An Lushan Rebellion (death toll: 13 – 36 million)

An Lushan RebellionSource and image: en.wikipedia.org

Another devastating war to have taken place in today´s China, the An Lushan Rebellion was a violent rebellion against the Tang dynasty that lasted from 755 AD to 763 AD.

There is no doubt that the rebellion resulted in a huge number of deaths, greatly reducing Tang empire’s population but the exact death toll is difficult to estimate even in approximate terms. Some scholars have assumed that up to 36 million people, about two-thirds of the population of the empire, might have died in the rebellion.


World War I (death toll: 18 million)

World War ISource and image: en.wikipedia.org

Fought between July 1914 and November 1918, the World War I was a global war that originated in Europe and gradually drew in all the world’s economic great powers that assembled in two opposing alliances: the Allies and the Central Powers.

The total number of deaths included about 11 million military personnel and about 7 million civilians. About two-thirds of military deaths in World War I was in battle, unlike the conflicts that took place in the 19th century when the majority of deaths were due to disease.


Taiping Rebellion (death toll: 20 – 30 million)

Taiping RebellionSource and image: en.wikipedia.org

Also known as the Taiping Civil War, the Taiping Rebellion was a massive rebellion in China that lasted from 1850 to 1864. The war was fought between the established Manchu-led Qing dynasty and the Christian millenarian movement of the Heavenly Kingdom of Peace.

There is no reliable census at the time but the most credible estimates put the total number of deaths during the rebellion at about 20 – 30 million civilians and soldiers. Most of the deaths were attributed to plague and famine.


Qing Conquest of the Ming (death toll: 25 million)

Qing Conquest of the MingSource and image: en.wikipedia.org

Fought between 1618 – 1683, the Qing conquest of the Ming (also known as the Ming–Qing transition) was a period of conflict between the Qing dynasty (a Chinese dynasty ruling contemporary Northeastern China) and the Ming dynasty (a Chinese dynasty ruling the south of the country).

The war that eventually resulted in the fall of the Mings caused death of about 25 million people.


Second Sino-Japanese War (death toll: 25 – 30 million)

Second Sino-Japanese WarSource and image: en.wikipedia.org

Fought between 1937 and 1945, the Second Sino-Japanese War was an armed conflict between the Republic of China and the Empire of Japan. After the Japanese attacked Pearl Harbor (1941), the war merged into World War II as a major front later known as the Pacific War.

The Second Sino-Japanese War was the largest Asian war in the 20th century, accounting for the majority of casualties in the Pacific War with up to 25 million Chinese civilians and over 4 million Chinese and Japanese military personnel dying from war-related violence, famine, and other causes.


Three Kingdom War (death toll: 36 – 40 million)

Three Kingdom WarSource and image: en.wikipedia.org

The Three Kingdom War was a series of armed conflicts in ancient China (AD 220–280). In the war, three states – Wei, Shu and Wu vied for power in the country, trying to unite the nations and take control over it.

One of the bloodiest periods in Chinese history, the Three Kingdom era was marked by a number of brutal battles that might have led to death of up to 40 million people.


Mongol Conquest (death toll: 40 – 70 million)

Mongol ConquestSource and image: en.wikipedia.org

Mongol invasions and conquests progressed throughout the 13th century, resulting in the vast Mongol Empire, which, by 1300, covered much of Asia and Eastern Europe. Historians regard the Mongol raids and invasions as some of the deadliest conflicts in human history. In addition, they brought the bubonic plague along with them, spreading it across much of Asia and Europe and helping cause the massive loss of life in the Black Death. The total death toll related to the conquest is estimated at 40 to 70 million.


World War II (death toll: 60 – 85 million)

World War IISource and image: en.wikipedia.org

Fought between 1939 and 1945, World War II was a global war that involved the vast majority of the world’s nations including all of the great powers. It was the most widespread war in history and directly involved more than 100 million people from over 30 countries.

Marked by mass deaths of civilians, including the Holocaust and the strategic bombing of industrial and population centers, it resulted in an estimated 60 million to 85 million fatalities, which made the World War II the deadliest conflict in human history.