The Worst Wars in History and How They Proved the Need for Peace

Throughout human history, our world has been ravaged by the devastation and suffering of war. Technology and human rights advances have not eliminated the use of violent means in resolving disagreements. With conflicts raging across the globe (and the threat of more), we are pressed to understand the impact of war. These five gruesome worst wars history that led to widespread bloodshed and suffering can give us perspective and inform the future decisions we make as a global community regarding creating a peaceful, humane, and just world. (Estimated reading time: 13-15 minutes)

“War does not determine who is right – only who is left.”

– Bertrand Russell

“Woe is me.”

These were the words uttered by Albert Einstein upon hearing news of the bombing of Hiroshima and Nagasaki in 1945.

Although he never worked directly on building the atomic bomb, his famous equation, E=mc2, explained the energy released in an atomic bomb. “I do not consider myself the father of the release of atomic energy. My part in it was quite indirect,” he often reminded people.

But there was another reason that Einstein felt partially responsible for the mass murder of an estimated 200,000 people, including women, children, sailors, and soldiers in the two Japanese cities.

Einstein, a lifelong pacifist, changed his stance when he sensed that the Second World War was an impending reality. Upon learning that the Nazis were close to developing nuclear weapons, he wrote to President Franklin Roosevelt with a warning, urging him to stockpile ore and begin the development of their own nuclear weapons.

After emigrating to the United States from Germany in December 1932 (a month before Adolf Hitler became chancellor), Einstein felt a sense of duty to his new home. His letter galvanized the U.S. effort to build an atomic bomb.

In 1941, after findings that proved creating a bomb was feasible, the government launched the Manhattan Project – a military and scientific initiative to develop nuclear weapons. Hundreds of scientists were recruited for the project, but they were forbidden to consult Einstein because it was seen as a potential security risk.

Six years later, the bombs known as Fat Boy and Little Man were dropped on Japanese soil. Einstein and the rest of the world witnessed the horror that ensued. Images of a massive mushroom cloud that rose to a height of more than 40,000 feet with an explosive yield comparable to 15,000 tons of TNT.

The detonations expedited the end of the Second World War, marking the beginning of the Cold War, a period of geopolitical tension between the U.S., the Soviet Union, and their respective allies, which dominated the second half of the 20th century.

When a Japanese journalist asked him why he cooperated in the production of the bombs, knowing full well of their destructive power, Einstein expressed deep regret for his actions.

“Had I known that the Germans would not succeed in producing an atomic bomb, I would never have lifted a finger,” Einstein said in a 1947 Newsweek article headlined “The Man Who Started It All.”

While the Nazis did not achieve nuclear armament because so many scientists had fled Nazi-occupied territory, the United States picked up from where they left off by providing safety for these defectors.

The devastation caused by the Hiroshima and Nagasaki bombings serves as a reminder of the potential of nuclear warfare to wipe out human civilization. Today, ten countries have nuclear arms which they can use in response to unprovoked aggression, and we must remain acutely vigilant of the threats it poses.

Albert Einstein vividly painted the consequences of its misuse when he said, “I do not know with what weapons World War III will be fought, but World War IV will be fought with sticks and stones.”

Roots of violence: why do people go to war?

For the past 2500 years of human history, our world has been ravaged by the devastation and suffering of conflicts and war. Advances in technology, human rights, and ethics have not slowed down the combative and reckless approach to resolving conflicts.

Many countries in Africa, the Middle East, and Asia are still experiencing terrorist insurgency and civil war. The most notable ones dominating the media are the ongoing Russia-Ukraine war and the recent Israel-Gaza conflict.

Humanity is baffled and devastated as the death toll in Israel and Gaza surges. It leaves many of us wondering why the deadly events of the past that took countless lives taught us anything. Why can’t we rise above these savage ways using the enlightened new ideas that made our civilizations prosper?

With conflicts raging across the globe, these questions have implications for understanding our past and future. Our propensity to engage in war and violent acts illustrates how our species is motivated by a hunger for power and wealth. Our reptilian brains, designed to protect us from threats to our survival, can also turn us into tyrannical power-mongers driven by greed.

The dark side of human nature is running the show when despots reduce people to bugs that must be squashed to further their agenda. Never mind the chaos, stagnation, famine, torture, and wasted time and resources that result, so long as they get what they want. Anyone who gets in the way or disagrees with them is instantly eradicated.

Humans, like other creatures, are territorial. We protect our territory by fighting with competitors for resources that sustain us, and mates to ensure the continuation of our species. However, two major differences exist in how we approach conflict compared to other animals.

First, we have the ability to organize massive fighting forces. Our warriors and soldiers are trained and armed with the finest technology and are at the disposal of a governing body that can tap into their human power when they need to go to battle. Because of this, the scale of damage and destruction humans can cause is bigger and more widespread than the isolated territorial disputes of the animal kingdom.

Second, unlike animals fighting for mates and limited resources, humans fight for cultural and ideological reasons. We will go to war to defend our tribes, values, beliefs, and honor. While many conflicts are motivated by economic reasons, a sizable chunk are driven by the need to uphold religious, political, and ideological beliefs tied to a group’s identity.

At our core, we are tribal. Tribes demand loyalty and, in return, offer us a sense of belonging. Members of social groups with a strong tribe mentality will go to great lengths to defend their group, including killing outsiders who threaten them and sacrificing their own lives to do so. 

The key to finding perspective when we find ourselves in the grips of combative urges is to rise above our basic instincts and channel wisdom from our higher minds, driven by rational thinking, and our hearts, driven by compassion and equanimity.

The five worst wars in history

Wars of all magnitudes have a lasting impact on the people directly affected by them. Throughout history, several conflicts have changed the course of humankind but also left scars.

These five gruesome worst wars in history resulted in ceaseless bloodshed, unprecedented suffering, and heinous crimes. This list can give us perspective on the feuds that took place on our planet, informing the future decisions we make as a global community.

1. Chinese Civil War (1927–1949)

The Chinese Civil War was fought between the forces of the Chinese Communist Party and the Kuomintang-led government of the Republic of China (KMT, or Chinese Nationalist Party). Both parties were fighting for the legitimacy of the government of China. This battle between warlords was led by Mao Zedong from the Communists and Chiang Kai-Shek from the Nationalists.

Like most civil wars in Chinese history, social disruption was the main cause of death. The fighting led to a rise in refugees who were vulnerable to starvation and disease. The mass atrocities carried out by both parties resulted in the deaths of 8 million people by 1950.

The war continued sporadically from 1927 to 1949 and ended with the victory of the Communist Party and the establishment of the People’s Republic of China under Mao Zedong’s leadership. This spurred significant change to the country’s social, political, and economic development.

The new government created a socialist state and the implementation of collectivization, land reform, and the suppression of political dissent. The war also hurt US-China relations and played a part in the emergence of the Cold War.

It’s worth pointing out that during the Second World War, KMT and CCP were able to temporarily put aside their differences and unite to fight against the Japanese who invaded their country in July 1937. However, after the Japanese surrendered, the Civil War in China resumed.

2. The Thirty Years’ War (1618-1648)

The Thirty Years’ War was a conflict fought between Catholic and Protestant states in Central Europe that lasted thirty years. However, as the war evolved, it became less about religious differences and more about which group would rule Europe.

The war escalated over the years and drew in great powers, including political leaders, who saw the conflict as an opportunity to shape Europe in a way that served their interests. They invested countless resources, including new military technologies like muskets and the pike, resulting in one of the longest and most destructive wars in European history.

It’s estimated that 8 million people perished due to the war, with countless injured. The immense destruction caused the bubonic plague, dysentery, and typhus to reach epidemic levels, and the bankruptcy from the war made it nearly impossible to clean up and rebuild Europe.

Peace was finally brokered with the signing of the Treaty of Westphalia in 1648. It opened the doorway for religious tolerance for Protestants in the Holy Roman Empire.

3. The War of Kalinga (262 BCE – 261 BCE)

The War of Kalinga was a significant conflict that took place in ancient India between the Mauryan Empire under Emperor Ashoka and the state of Kalinga, an independent feudal kingdom located on the east coast in the present-day state of Odisha and northern parts of Andhra Pradesh. It’s considered one of the largest and deadliest battles in Indian history.

The war arose due to Ashoka’s ambition to occupy Kalinga and make it part of his empire. It was also triggered by the Mauryan leaders’ refusal to submit to him and pay tribute. Ashoka’s army invaded Kalinga using their superior warfare and military tactics to defeat the soldiers of Kalinga and were eventually victorious.

However, the wars were marked by gruesome violence, with an estimated 100,000 soldiers and civilians killed and many more injured. Witnessing the devastation caused by his order to invade Kalinga profoundly impacted Ashoka. He vowed never to use violence to resolve conflicts and embraced Buddhism, becoming a figure for social justice and non-violence, promoting human rights, morality, and religious tolerance for the rest of his rulership.

4. Mongol conquests and invasions (1211-1337)

The Mongols, a tribe of nomadic horsemen from Central Asia, developed a reputation as a fearsome, undefeated fighting force who brutally conquered territories.

With fierce and menacing leaders like Genghis Khan and, later, his grandson, Kublai Khan, there was no stopping their military power. Ian Frazier wrote in The New Yorker, “For the cities and cultivated places in the Mongols’ path, they were a natural disaster on the order of an asteroid collision.”

These forbidding warriors conducted a hundred-year campaign, capturing almost 20 percent of the land on Earth, with an empire encompassing Asia and Eastern Europe. They invaded the lands that now cover modern-day China, Russia, Iran, Iraq, Hungary, Poland, and several other territories.

The Mongol conquests led to the deaths of 11.5 million people, according to revisionist studies done by historians. Mongols exaggerated the number of killings in their conquests by up to 70 million to instill fear and demoralize those on their conquest agenda.

An example of the brutality of the Mongol forces is when they invaded the Persian city of Nishapur, where they murdered 1.7 million people living in and around the city. They went on a killing spree in Baghdad, wiping out 200,000 to 1 million inhabitants. It’s also believed that 100,000 Chinese people committed mass suicide to avoid falling into the hands of the blood-thirsty Mongols.

5. World War II (1939-1944)

The Second World War (or World War II) was a massive global conflict involving almost all nations. It began when Nazi Germany invaded Poland in 1939, prompting France and Great Britain to declare war against Germany.

The war was fought on several fronts, including Africa, Asia, and Europe. The stakes increased with new military technologies like radar, jet propulsion, and atomic bombs. For instance, strategic aerial bombings exacerbated civilian killings. The war also saw horrific crimes such as ethnic cleansing and mass genocide. 

The war snowballed into the development of the Axis Powers (led by Germany, Italy, and Japan) and the Allied Powers (led by the United States, Great Britain, and the Soviet Union) who fought against each other. These military alliances engaged in war for nearly six years, causing the deaths of an estimated 100 million military personnel from thirty different countries and destroying thousands of cities.

The damage was worsened by the occupation of several territories by the brutal Axis Powers. Their actions were responsible for the suffering and deaths of millions of civilians in countries like Poland, Yugoslavia, the Soviet Union, and others where disease and starvation became widespread.

Genocide campaigns like the infamous Holocaust orchestrated by Hitler caused the deaths of 50 million Jewish people. Other ethnic groups affected included Roma, Slavs, German dissidents, homosexuals, and disabled people. The horrific events of World War II left an indelible impression on humanity and caused a seismic shift in the way we approach politics and handling conflict.

Other deadly wars that caused turmoil and a large number of deaths: Tai Ping Rebellion, World War I, the American Civil War, the Second Sino-Japanese War, the Dungan Revolt, the Russian Civil War, the Qing Dynasty Conquest of the Ming Dynasty, the An Lushan Rebellion, the Second Congo War, the Napoleonic Wars.

Is it possible to reach a resolution without armed conflict?

War has a catastrophic impact on the wellbeing and health of countries. Studies show that conflicts cause more death and disability than any major disease. It destroys families, communities, and damages the economic and social fabric of a country.

The effects of war also have a psychological and physical impact that can last a lifetime. Besides the casualties of war, economic and social decline, poverty, disability, and malnutrition are some of the many fallouts of war.

There are no long-term winners in war. Winners in one war become losers in the next, as history has shown us. War heroes in one nation are criminals to those they fought against. Conflicts are relentless, pointless, and endless if we don’t take a moment to step back and see the forest for the trees.

If not war, what else can countries do to resolve disagreements and conflicts of interest? First,  we can elect leaders who have the wisdom and foresight to negotiate and cooperate in ways that preserve their countries while creating a win-win agreement. Former U.S. president Jimmy Carter displayed this ability when he brokered a peace deal, The Camp David Accords, between Egyptian President Anwar Sadat and Israeli Prime Minister Menachem.

In contrast, notorious figures like Genghis Khan and Adolf Hitler displayed a ruthless type of leadership where they only looked to get what they wanted at the expense of others. While they were brilliant strategists and skilled at warfare, their reigns of terror overshadowed them.

No matter how well-versed leaders are in governance and tactics, their success will only be positively lasting and impactful if they execute that knowledge with insight, empathy, and sound judgment.

Mahatma Gandhi said, “Whenever you are confronted with an opponent. Conquer him with love.” He and other great leaders, like Martin Luther King Jr. and Nelson Mandela, eventually conquered their opponents with love. Gandhi pioneered the idea of ahimsa (doing no harm) common to Buddhism and Hinduism and turned conquest into a nonviolent movement for mass action to win India’s freedom.

Ethical non-violence goes deeper than words and actions and speaks to developing character. It’s building the capacity to develop empathy, hold love for everyone (including those who disagree with you), and avoid developing hate. War goes against this, fanning the flames of tribalism, nationalism, and ethnic and racial divides. All of these divisions are products of the primitive mind.

The good news is that we construct these divisions, so we have the power to deconstruct them and build a better model of the world. Recently, several peaceful protests have successfully led to social and political change. These stances against inequality and injustice show that non-violence can be a potent way to achieve systemic change.

This happens when people realize that we all share the same goal: to create a healthy, prosperous, and sustainable planet where every creature can flourish. We saw this occur in The Singing Revolution of the Baltic Revolution in the late 1980s and the Montgomery Bus Boycott of the Civil Rights Movements in the U.S.

War does not serve this common goal but threatens it. Organizations such as the United Nations recognize this and send peacekeeping forces to resolve conflicts to keep both sides from killing each other and making peace.

However, we can’t rely on external bodies to clean up the mess in our own backyards. We need effective and coherent strategies to resolve our differences, beginning with changing our mindset. We must collectively acknowledge that healthy compromise is the soul of progress.

Change can be slow, but we must stick with it. Instead of seeking an immediate resolution that can cause us to act hastily, which can be self-destructive and short-sighted, we wait and aim for social progress instead. If we plant the seeds now, we’ll grow a new generation of people with ideals and an ethical code guiding them toward love and peace rather than hate and fear.

War is rarely a dispute about what’s right and what’s wrong. It’s always about a bid for power and who can gain more at the expense of others. As we continue to witness scenes of panic and devastation in countries still ravaged by the flames of war, let’s remember the lessons about what losses such conflicts can bring. We can do much better in a world that’s now driven to support world peace and humanitarian rights, but only if we tap into our hearts and humanity.

All my best on your journey,

Seline

Questions for you: Which of these worst wars in history do you consider the worst, and why? What is the key takeaway from this event?

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