History of war

The Peloponnesian War explained: from 431 to 404 BC, Athens and its Delian League allies fought Sparta and the Peloponnesian League for hegemony over Greece. Plague, the disastrous Sicilian Expedition, and Persian money decided a war that ended Athens' empire and its golden age.

From 264 to 146 BC the Roman Republic and Carthage fought three wars — 43 years of actual fighting — for the western Mediterranean. Hannibal's march over the Alps and the slaughter at Cannae are the famous episodes; the endpoint was the siege and razing of Carthage and Rome's emergence as an imperial power.

The Hundred Years' War (1337–1453) was an intermittent 116-year struggle between England and France over the French throne and English lands in France. Opening English victories at Crécy and Poitiers gave way to a French recovery crowned by Joan of Arc — and a final French victory that reshaped warfare, taxation, and the modern state.

From the Defenestration of Prague in 1618 to the Peace of Westphalia in 1648, a Bohemian revolt over religion mutated into a continental power struggle that killed an estimated 4.5–8 million people, redrew the map of Europe, and laid the foundations of the modern state system.

The Seven Years' War, explained: fought from 1756 to 1763 across Europe, North America, India, the Caribbean, and West Africa, it was the first truly global war — a conflict Winston Churchill's chapter on it calls 'The First World War.' It ended with Britain dominant, France's colonial empire destroyed, and Prussia confirmed as a great power.

The War of 1812 (1812–1815) began with British seizures of American ships and sailors and ended in a draw the treaty barely mentioned. Fought mainly over neutral trading rights, it failed to conquer Canada, burned Washington, killed some 37,000 people across three nations — and left the United States, Canada, and Britain's relationship permanently changed.

From about 1800 to 1815, Napoleonic France fought shifting alliances across the continent, ending at Waterloo. The wars cost hundreds of thousands of lives, strained treasuries to breaking point, and redrew Europe's map at the Congress of Vienna.

Fought from 1853 to 1856 between Russia and an alliance of Britain, France, the Ottoman Empire, and Sardinia, the Crimean War introduced rifled guns, the war correspondent, and the telegraph — and its fallout reshaped Europe.

The American Civil War (1861–1865) killed between 620,000 and 850,000 soldiers, ended slavery, and redefined the United States. Here is what caused the war, what it cost, and how it reshaped America.

The Austro-Prussian War of 1866 — the Seven Weeks' War — was Bismarck's deliberately staged showdown for the leadership of Germany. Prussia crushed Austria at Königgrätz on 3 July, dissolved the German Confederation, created the North German Confederation, and settled the 'German question' on Prussian terms. Austria lost no territory but was expelled from German affairs; Italy gained Venetia.

The Franco-Prussian War of 1870–71 destroyed the Second French Empire, killed an estimated 180,000–200,000 soldiers, cost France five billion francs and Alsace-Lorraine, and created a unified German Empire — the power shift that shaped Europe until 1945.

In 1904–05, Japan — barely a generation removed from feudal rule — fought Russia to a standstill and won. It was the first modern victory of an Asian state over a European great power, and its shockwaves ran from Tokyo's bond markets to the streets of St. Petersburg.

In less than a year, two Balkan wars stripped the Ottoman Empire of almost all its European territory, doubled Serbia and Greece, and lit the fuse of 1914. Why the wars started, what they cost, and why historian Richard C. Hall calls them the first phase of the First World War.

From July 1936 to April 1939, Spain tore itself apart between a Republican government backed by the Soviet Union and international volunteers, and Nationalist rebels armed by Nazi Germany and Fascist Italy. Around 500,000 people died — and the world watched a preview of the coming global war.

World War I (1914–1918) killed millions, toppled four empires, and redrew the map of Europe. This explainer covers the causes of World War I, its casualty figures, economic fallout, and lasting legacy.

World War II (1939–1945) killed an estimated 40–50 million people, making it the deadliest war in history. This explainer covers the causes of World War II, its casualties, economic aftermath, and the institutions — from the UN to the Marshall Plan — it left behind.

The Korean War (1950–1953) killed millions, ended in an armistice rather than a peace treaty, and left the peninsula divided to this day. Here is why it started, what it cost, and why it still matters.

The Vietnam War killed millions and reshaped American institutions, Southeast Asia's borders, and Cold War politics — this explainer covers the causes, the casualty ranges, the economic costs, and the global consequences.

The Soviet-Afghan War (1979–1989) trapped a superpower in a grinding counterinsurgency, killed around 15,000 Soviet troops, displaced a third of Afghanistan's people, and ended with the withdrawal completed on February 15, 1989.

The Iran-Iraq War (1980–1988) was the longest conventional war of the 20th century: Iraq's invasion of post-revolutionary Iran became a trench-warfare stalemate with chemical weapons, the Tanker War, and total casualties estimated at one to two million. It ended with the borders unchanged.

The Falklands War explained: from 2 April to 14 June 1982, Argentina and the United Kingdom fought a 74-day undeclared war over the Falkland Islands (Islas Malvinas), South Georgia and the South Sandwich Islands. Argentina invaded; a British task force sailed 8,000 miles to retake them. 907 people died, Argentina's junta fell, and the sovereignty dispute remains unresolved.

Iraq's 1990 invasion of Kuwait triggered a UN-authorized coalition and a lightning campaign that ended in decisive victory — and left Saddam Hussein in power. The Gulf War was the first major crisis of the post-Cold War era, and its unfinished business led straight to 2003.