The 7 Most Unfair Wars in History (And Why They Still Matter)

What Makes a War “Unfair”?

Throughout history, wars have been fought for power, land, religion, and revenge. But some wars stand out not just for their brutality, but for their sheer injustice. These are conflicts where one side had overwhelming power, manufactured a pretext, or targeted a weaker opponent with little or no justification.

Here are seven of the most one-sided and unjust wars in world history, and why they still echo today.

1. The Opium Wars (1839–42, 1856–60)

Who: Great Britain vs. Qing China Where: China Why It Was Unfair: Drug profits over national sovereignty

In the early 19th century, Britain faced a trade imbalance with China. To offset it, British merchants began exporting Indian opium to Chinese ports, causing widespread addiction and social decay. When the Qing government banned the drug and seized British shipments, Britain retaliated, not with diplomacy, but with war.

Armed with modern gunships and superior firepower, Britain crushed Chinese coastal defenses in the First Opium War, forcing China to sign the Treaty of Nanjing (1842). This "unequal treaty" ceded Hong Kong to Britain and opened several ports to foreign control. The Second Opium War deepened the humiliation, leading to the looting and burning of Beijing’s Summer Palace.

2. The Spanish Conquest of the Aztecs (1519–1521)

Who: Spanish Empire vs. Aztec Empire Where: Central Mexico Why It Was Unfair: A technologically superior force wiped out a civilization through treachery and disease

Led by Hernán Cortés, a few hundred Spanish soldiers overthrew the massive Aztec Empire. They exploited internal rivalries, captured Emperor Montezuma, and seized Tenochtitlán with help from local enemies of the Aztecs. Crucially, smallpox, brought by the Europeans, decimated indigenous populations.

The conquest wasn't just a military victory. It marked the beginning of European colonization of the Americas, bringing forced conversions, slavery, and cultural genocide. The Aztec economy, religious traditions, and social structure were destroyed within years. 3. The Anglo-Zulu War (1879)

Who: British Empire vs. Zulu Kingdom Where: Southern Africa Why It Was Unfair: Manufactured conflict used to justify colonial takeover

The Zulu Kingdom, led by King Cetshwayo, posed no threat to Britain. But colonial authorities in South Africa wanted control of Zulu land. They issued an ultimatum designed to be rejected—and when it was, they invaded.

The war began with a shocking Zulu victory at the Battle of Isandlwana, where British troops were nearly annihilated. But Britain sent reinforcements and retaliated with overwhelming force, eventually capturing the Zulu capital and breaking the kingdom’s independence.

4. The U.S. Invasion of Iraq (2003)

Who: United States and coalition forces vs. Iraq Where: Iraq Why It Was Unfair: War based on false intelligence and no direct provocation

In 2003, the U.S. government claimed that Iraq possessed weapons of mass destruction (WMDs) and posed an imminent threat. No such weapons were ever found. Iraq also had no involvement in the 9/11 attacks. Yet the invasion moved forward, toppling Saddam Hussein’s regime.

The war caused hundreds of thousands of civilian deaths, destabilized the region, and gave rise to terrorist groups like ISIS. Years later, multiple investigations revealed the intelligence was deeply flawed, if not deliberately distorted.

5. The Belgian Colonization of the Congo (1885–1908)

Who: King Leopold II of Belgium vs. Congolese peoples Where: Central Africa Why It Was Unfair: A personal colony run like a slave state

At the Berlin Conference in 1885, King Leopold II of Belgium claimed the Congo Basin as his private property—the Congo Free State. Under the guise of philanthropy and civilization, Leopold oversaw a brutal regime of forced labor, mutilation, and execution.

Entire villages were enslaved to harvest rubber. Hands were cut off to enforce quotas. Estimates suggest 10 million Congolese died from exploitation, starvation, and violence. 6. The Japanese Invasion of Manchuria (1931)

Who: Empire of Japan vs. China Where: Northeast China (Manchuria) Why It Was Unfair: A false-flag attack used to justify occupation

Japan engineered a fake explosion on a railway it controlled near Mukden and blamed Chinese troops. This “Mukden Incident” was used as a pretext to invade Manchuria. Within months, Japan had established the puppet state of Manchukuo, installing a former Qing emperor as a figurehead.

Despite condemnation from the League of Nations, Japan faced no meaningful punishment and eventually withdrew from the League. This emboldened further aggression, leading to full-scale war in 1937 and eventually World War II in the Pacific.

7. The Mexican-American War (1846–1848)

Who: United States vs. Mexico Where: Mexico and the U.S. Southwest Why It Was Unfair: A war of expansion cloaked in patriotism

Driven by Manifest Destiny, the belief that the U.S. was destined to expand coast-to-coast, President James K. Polk provoked war with Mexico by sending troops into disputed territory near the Rio Grande.

After U.S. forces captured Mexico City, the Treaty of Guadalupe Hidalgo forced Mexico to cede half its national territory, including present-day California, Arizona, New Mexico, and Texas.

Even Ulysses S. Grant, who fought in the war, later wrote: “I do not think there was ever a more wicked war… and I have never seen a more wicked peace.”