Top 10 Worst Wars in History

War is a grim topic, but an important one to tackle. Understanding the scale, devastation, and consequences of these conflicts helps us grasp the sheer weight of human choices, geopolitics, and, unfortunately, the darker sides of our nature.

This, however, isn't just about doom and gloom. It's about learning and awareness. If history teaches us anything, it's that we're bound to repeat mistakes if we're not vigilant. So, as you go through this list, consider what led to these devastating wars and what could have been done differently.
The Top Ten
1 World War II The conflict resulted in the loss of an estimated 70–85 million lives, which was approximately 3% of the world's population at that time. It was marked by atrocities such as the Holocaust, where six million Jews were exterminated. Cities across Europe and Asia were reduced to rubble, impacting millions and disrupting civil life on an unprecedented scale.

The only war that had nuclear bombings was World War II. This war had the most casualties in human history and involved the most countries. All of the Americas, all African states at the time (Liberia and Ethiopia), all countries in the Middle East (except Yemen), all countries in Asia (except Tibet, Bhutan, and Afghanistan), all Oceania countries, and almost all of Europe participated (with the exception of the Baltic states, Sweden, Switzerland, Vatican, Andorra, Spain, Portugal, and Liechtenstein - even though the Japanese invaded their Timor colony).

The most casualties were in the Soviet Union and China. Multiple atrocities were committed during the war. For example, my great-grandmother's house was bombed during the Battle of Britain. This war shaped the Cold War and most of the modern-day world.

2 World War I This war saw the first large-scale use of chemical weapons and tanks, leading to widespread suffering and death. It resulted in an estimated 16 million deaths and 21 million wounded, not to mention the psychological toll it took on an entire generation. The war led to the collapse of empires and a re-drawing of national boundaries, sowing the seeds for future conflicts.

I'm not sure about the death toll, but for sheer horror, WWI is definitely worse than WWII. A sampling of the horrors includes poison gas, trenches, mortars, bombs, machine guns, and tanks - most of them seen for the first time.

WWII was bad for sure, but it also shaped the way the world is today, further elevating the US, the next generation, and the women's movement, to name a few.

World War I was the deadliest conflict ever. It killed 17 million people. It was thought to be the war to end all wars because of the deadly impact on countries. The Allies won.

3 Napoleonic Wars Lasting over a decade, these wars led to a conservative estimate of 3.5 million deaths, both military and civilian. The Continental System led to economic hardship and famine in several European countries. The invasion of Russia, marked by a disastrous retreat, demonstrated the human cost of military hubris, with the vast majority of the Grande Armée perishing.

You mean "Invasion of the Little Corporal."

4 Vietnam War The use of Agent Orange and other herbicides by the U.S. led to long-lasting environmental damage and health issues among the Vietnamese population. The war resulted in an estimated 2–3 million Vietnamese deaths and over 58,000 U.S. military deaths. Widespread protests and a deeply divided American public marked the domestic response, eroding faith in the government.

Everybody was divided in those times. College students everywhere tried protesting, but the police stopped them dead in their tracks. Then, the U.S. government began conscripting, and a few of the lucky ones emigrated to the Great White North. If we could turn back time, this war would have never happened. (Also, we would have been more optimistic, and Annie would've been on Broadway sooner).

A hard-fought war that turned out to be pointless. Sure, the U.S. mission there was to contain communism, but the very nation they were backing was corrupt and unpopular among the people. Fast forward, and they lost with a lot of American blood wasted. Today, "communist" Vietnam is on good terms with the U.S.

5 American Civil War This conflict resulted in approximately 620,000 soldier deaths, more than any other war in American history. Slavery was a key issue, and the war led to the emancipation of nearly 4 million enslaved African Americans, but not without immense human cost. Families were often torn apart, fighting for opposing sides, and the southern U.S. was left in economic ruin.

The North really wanted the South to adapt to their way of life by taking the southern folks' property away from them. This war created the madman John Wilkes Booth.

Yes, it was! It didn't matter how inaccurate muskets were. People had new weapons to mow down the enemy in brutal, nasty ways!

"Not deadly," yet it's called the bloodiest war in American history and had the most American deaths. Many of them were from diseases, and family members were killing each other. It also led to the death of Abraham Lincoln. I wouldn't say this is the worst war in world history, but definitely in American history.

6 Thirty Years' War The war decimated the population of the Holy Roman Empire, with estimates suggesting that nearly 30% of its people were killed. In certain areas, up to 50% of the population died due to combat, famine, or disease. The war was marked by the frequent sacking of cities and towns, leading to widespread suffering and displacement.

Thirty years of hell and starvation completely depopulated huge areas in Germany. The reasons for the war are complex, and alliances shifted constantly. It started as an internal conflict, but soon foreign powers intervened for various reasons, mostly to expand their wealth, influence, and power.

Cardinal Richelieu, the bad guy from the Three Musketeers, was the biggest influence behind the reason why the war escalated and lasted so long. In the end, the only ones who really profited from the war were France and Sweden.

Sweden became a great power for a while, after getting rich from war booty by plundering major German cities. France became the undisputed hegemon of Europe for the next 200 years since there was no real opposition left on the continent.

It would take 150 years until the population of the German states was on the same level as before the war, and any centralized institutions de facto stopped existing.

7 Russian Civil War An estimated 7–12 million casualties were sustained, a significant portion of which were civilians. The conflict led to widespread famine, notably the Russian Famine of 1921, which cost an additional several million lives. The Red Terror and the White Terror contributed to political repression and extrajudicial killings.

This was the worst European war after WWI and WWII. Millions were killed, the war had more than 10 factions, and it covered an area of 20 million kilometers. I can't find a worse European war, excluding the world wars.

8 Chinese Civil War The conflict led to an estimated 2–3 million military deaths and a much higher number of civilian casualties. Widespread poverty and displacement were rampant, as families and communities were torn apart. Hyperinflation and economic hardship gripped the country, leading to additional suffering.

This war is what turned democratic China into a communist state.

9 Hundred Years' War The lengthy conflict drained the resources of both England and France, leading to economic hardship for commoners. Heavy taxation to fund the war led to revolts and social unrest in both countries. The war also left a legacy of festering Anglo-French animosity, which persisted for centuries.

How could they have a war for a hundred years? The idiots in the world should've realized that they should've stopped wars after this.

10 Iran-Iraq War The conflict was marked by the use of chemical weapons against both combatants and civilians, notably by Iraq. It led to an estimated 1 million deaths and crippled the economies of both nations. Child soldiers were used, particularly by Iran, contributing to the conflict's high human cost.
The Contenders
11 English Civil War The conflict led to an estimated 200,000 deaths, out of a population of around 5 million, resulting in a higher proportional fatality rate than World War I for England. This war led to social upheaval and regicide, with the execution of King Charles I. Families were often pitted against each other, with brother fighting against brother.
12 War in Afghanistan The protracted conflict led to tens of thousands of Afghan civilian deaths and displaced millions. The use of drone strikes led to unintended casualties, often affecting non-combatants. The instability allowed for the rise of extremist groups, affecting regional and global security.

So, Bush the Tush, you think it's good to blame an entire country for a terrorist attack.

13 Trojan War While the historical authenticity of the Trojan War is debated, its portrayal in epic poems like the "Iliad" depicts extensive loss of life and heroism tinged with futility. The famous story of the Trojan Horse exemplifies the deceit and trickery that led to the fall of Troy. The war, as described in myth, resulted in the deaths of legendary figures such as Hector and Achilles and brought ruin to the city of Troy.
14 American Revolutionary War While the human cost was relatively lower compared to other wars, an estimated 25,000 American deaths still marked significant loss. The conflict left American cities like New York and Charleston heavily damaged and resulted in economic hardship due to blockades. The war also had global implications, encouraging revolutionary movements in other parts of the world.
15 Spanish Civil War The conflict resulted in an estimated 500,000 deaths, and led to the rise of the fascist dictator Francisco Franco. The bombing of Guernica and other civilian targets exemplified the brutality of the warfare, setting a precedent for aerial bombardments in subsequent conflicts. The war became a symbol of divided ideologies, not just within Spain but throughout Europe, and served as a precursor to World War II.
16 Korean War An estimated 2.5 million people lost their lives in this conflict, which also separated families across the Korean Peninsula, many of whom are still divided. Cities like Seoul were captured and recaptured multiple times, resulting in significant civilian suffering and material destruction. The war ended in an armistice, not a peace treaty, leaving the two Koreas in a state of technical war to this day.

Any civil war is terrible. Brother fighting against brother should not happen. What makes this the worst is that we are still divided.

17 First Chechen War The conflict resulted in tens of thousands of deaths, a large proportion of whom were civilians. The capital, Grozny, was reduced to ruins due to Russian artillery and air strikes. The war also led to a humanitarian crisis, with hundreds of thousands of people displaced from their homes.
18 Irish Rebellion of 1798 The rebellion led to an estimated 10,000 to 50,000 deaths, a devastating number for the Irish population at the time. The conflict was marked by brutal reprisals and massacres committed by both sides. The failure of the rebellion led to the Act of Union in 1800, which dissolved the Irish Parliament and brought Ireland under closer British control.
19 Three Kingdoms War (China) This war led to an estimated 36–40 million deaths, according to historical records, making it one of the deadliest conflicts in history. The protracted period of warfare led to significant societal upheaval and fragmentation of the Chinese empire. Famines and peasant uprisings were widespread, adding to the chaos and human suffering.
20 Syrian Civil War The conflict has resulted in hundreds of thousands of deaths and the displacement of millions, creating one of the worst refugee crises in modern history. The use of chemical weapons on civilian populations drew international condemnation. Cities like Aleppo have been reduced to ruins, and countless cultural heritage sites have been destroyed.
21 Pig War Although no human lives were lost in this boundary dispute between the United States and Britain, the escalation to a military standoff over the killing of a pig exemplified the precariousness of international relations. The deployment of warships and troops for such a minor incident highlighted how easily nations could be drawn into conflict. Fortunately, the war ended peacefully, but not without straining U.S.-British relations.
22 Iraq War The conflict resulted in an estimated 100,000 to 600,000 Iraqi deaths and over 4,400 U.S. military deaths. The breakdown of civil order led to sectarian violence and the rise of extremist groups like ISIS. The use of "shock and awe" bombing tactics and the controversy over weapons of mass destruction undermined global confidence in U.S. foreign policy.
23 Croatian War of Independence The conflict resulted in about 20,000 deaths and displaced many others. Cities like Vukovar were subjected to extended sieges, leading to significant loss of life and infrastructure. Ethnic tensions and atrocities, such as the mass killing of civilians, further exacerbated the human cost of the conflict.
24 Bosnian War of Independence The war was marked by the Siege of Sarajevo, which lasted for nearly four years and resulted in thousands of civilian deaths. Ethnic cleansing and the Srebrenica massacre, in which around 8,000 Bosniak men and boys were killed, exemplified the atrocities committed. The conflict left Bosnia and Herzegovina deeply divided along ethnic lines, with lasting repercussions for the region.
25 War of 1812 The conflict led to several thousand deaths and weakened Native American resistance against American expansion. Cities like Washington, D.C., were burned, impacting the national psyche. The war ended without resolving many of the issues that had sparked it, leaving both the United States and Britain with lingering grievances.
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