The Second World War was a global conflict fought between 1939 and 1945 involving almost every country on Earth. On one side were the Allies — mainly Britain, France, the Soviet Union, the United States, and dozens of other countries. On the other were the Axis Powers — Germany, Japan, and Italy.
It was the deadliest event in human history. Estimates vary, but between 70 and 85 million people died — about 3% of the entire world population at the time. The majority were civilians.
How did it start?
The seeds were planted at the end of the First World War (1914–1918). The Treaty of Versailles placed enormous blame and punishing reparations on Germany, causing severe economic hardship and national humiliation. In this environment of poverty and resentment, Adolf Hitler and the Nazi party rose to power in Germany in 1933, offering simple answers and scapegoats.
Hitler's ideology was built on extreme nationalism, racism, and the belief in German racial superiority. He began rebuilding Germany's military in defiance of the peace treaty and, in 1938–39, started annexing neighbouring territories. When Germany invaded Poland on 1 September 1939, Britain and France declared war.
Think of it this way: Germany lost the First World War, and the punishment was so harsh it was like losing a fight, then having someone take your wallet, your shoes, your coat, and tell everyone what a terrible person you are. Bitterness that severe creates dangerous conditions for people like Hitler, who said: "I know who did this to you — follow me and I'll fix it." This is why historians say the Second World War grew out of the unresolved wreckage of the First.
What was the Holocaust?
The Holocaust was the systematic murder of approximately six million Jewish people by the Nazi regime — along with millions of others: Roma people, disabled people, political prisoners, gay people, and others the Nazis deemed undesirable. People were rounded up, transported to concentration camps, and killed on an industrial scale. It remains the most well-documented genocide in history and a defining lesson about what happens when hatred is given political power.
How did it end?
By 1944, the Allies had landed in France (D-Day, June 1944) and were pushing into Germany from the west. Soviet forces were advancing from the east. Germany was caught in a vice. Hitler died on 30 April 1945; Germany surrendered on 8 May 1945 — V-E Day (Victory in Europe). Japan surrendered in August 1945 following the American atomic bombing of Hiroshima and Nagasaki.
What changed afterwards?
The world was rebuilt around the determination that this must never happen again. The United Nations was founded. The Universal Declaration of Human Rights was written. Germany was divided and rebuilt under Allied oversight. The Cold War began between the US and Soviet Union. The modern world — its institutions, its borders, its rules — was largely shaped by the lessons and consequences of 1939–1945.