10 Biggest Wars in History With Death Tolls in the Tens of Millions

World War II remains the deadliest war in human history. The global war lasted from 1939 to 1945 and involved dozens of countries across Europe, East Asia, the Pacific, and the Middle East.

The conflict began after the rise of fascism and the expansion of Nazi Germany, which was partly fueled by resentments from the Treaty of Versailles following the First World War.

Germany, Italy, and Japan formed the Axis Powers while Allied forces included countries such as Great Britain, the Soviet Union, and the United States.

The war expanded dramatically after the attack on Pearl Harbor in 1941, bringing many Americans and large American forces into the conflict. Fighting stretched from Western Europe to Eastern Europe and across the Pacific.

Modern historians estimate that nearly 70 million people died during the Second World War. A large portion of that death toll consisted of civilians, including Jewish people targeted during the Holocaust.

The Mongol Conquests of the 13th century created the largest contiguous land empire in history. Under the leadership of Mongol armies, territories across East Asia, Central Asia, the Middle East, and Eastern Europe were conquered.

Estimates of deaths during these campaigns are uncertain and vary widely. Despite the destruction, the Mongol Empire also connected trade routes across Eurasia.

This period helped create what historians call the Pax Mongolica, a time when trade and cultural exchange increased along the Silk Road.

The Taiping Rebellion in China ranks among the deadliest civil wars in history. The conflict began in 1850 and lasted until 1864 during the late Qing dynasty.

The rebellion involved massive armies and prolonged fighting across central China. Many civilians died as famine, displacement, and warfare spread across large regions.

Modern estimates place the death toll between 20 million and 30 million people. The conflict weakened the Qing government and helped push China toward modernization efforts.

World War I, often called the Great War, lasted from 1914 to 1918. The war began after the assassination of Archduke Franz Ferdinand in Austria-Hungary.

European powers quickly mobilized into opposing alliances. The Central Powers included Germany, Austria-Hungary and the Ottoman Empire, while the Allies included Great Britain, France, Russia, and later the United States.

The First World War became famous for trench warfare along the Western Front. Millions of military personnel and civilians died as new weapons and industrial-scale combat reshaped warfare.

The Second Sino-Japanese War began in 1937 and later merged into the broader conflict of World War II. Fighting took place primarily in East Asia as Japan expanded its imperial ambitions in China.

The war produced widespread civilian deaths and destruction across Chinese cities and countryside. Historians estimate that between 15 million and 20 million people died during the conflict.

The scale of violence and displacement made it one of the most devastating wars in Asian history.

The Russian Civil War followed the Russian Revolution and lasted from 1917 to 1922. Competing political groups fought for control of the former Russian Empire.

The conflict included the Bolshevik Red Army and several anti-communist forces known collectively as the White Army. The outcome eventually led to the creation of the Soviet Union.

Civilian suffering played a major role in the death toll as famine, disease, and political violence spread across Eastern Europe and northern Asia.

The Thirty Years War devastated Central Europe between 1618 and 1648. The conflict began as a religious struggle within the Holy Roman Empire but eventually involved many European nations.

Fighting spread across Germany and surrounding regions. Armies destroyed farms and towns while famine and disease killed large numbers of civilians.

Historians estimate about 8 million deaths occurred during the conflict. The war ended with the Peace of Westphalia.

The American Civil War lasted from 1861 to 1865. The conflict erupted between the Union and the Confederacy over issues including slavery and federal authority.

President Abraham Lincoln led the United States during the war while Union and Confederate armies fought across the country. Early battles and later campaigns produced enormous casualties among soldiers and civilians.

The war ultimately preserved the United States and ended legalized slavery, reshaping American society and government.

The Vietnam War lasted from 1954 to 1975 and became one of the defining armed conflicts of the Cold War era. Fighting centered on North Vietnam and South Vietnam but expanded across Southeast Asia.

American forces joined South Vietnam while North Vietnam received support from communist allies. The war caused widespread civilian deaths and long-term political consequences throughout the region.

The conflict also deeply affected public opinion and global politics during the second half of the 20th century.

The Korean War began in 1950 when North Korea invaded South Korea across the Korean Peninsula. The conflict quickly drew in international forces.

United Nations troops, including many American forces, supported South Korea while China backed North Korea. Heavy fighting lasted until an armistice in 1953.

The war ended without a formal peace treaty, leaving the Korean Peninsula divided by the Demilitarized Zone that still exists today.

Military history education often studies wars like these to understand how armed conflicts reshape societies. These events changed borders, created new nations and influenced human rights debates, technological development, and the balance of global power.

We created this article in conjunction with AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.