World war

A world war is an international conflict involving most or all of the world's major powers. While many large conflicts have occurred, the term is conventionally reserved for two massive wars in the 20th century. These are World War I (1914–1918) and World War II (1939–1945). Some historians also use the term for other global struggles. These include the Cold War and the War on Terror.

The concept of a "world war" has appeared in different forms throughout history. In 1848, a Scottish newspaper used the term to describe a war among great powers. Later, Karl Marx and Friedrich Engels used it in articles about class struggles. In 1889, Rasmus B. Anderson described a mythic war as a "world war." By 1914, the biologist Ernst Haeckel predicted the European War would become the first world war. The specific phrase "World War I" was later coined by Time magazine in 1939. The term "World War II" was also used by the magazine during that same year.

World War I took place from 1914 to 1918. It was fueled by the Second Industrial Revolution and increased globalization. This era allowed for the mass production of military hardware. The war was triggered by a complex system of military alliances. The German and Austro-Hungarian Empires were allied against the British, Italian, Russian, and French Empires. A small conflict between two nations could cause a domino effect through these alliances. Because many powers held large overseas empires, the fighting spread across many continents.

World War II lasted from 1939 to 1945. This conflict featured the Axis powers, which included Nazi Germany, the Empire of Japan, and the Kingdom of Italy. They fought against the Allied powers, known as the "Big Four." These Allies were the United Kingdom, the United States, the Soviet Union, and China. This war was unique because it was the only conflict where nuclear weapons were used. The United States dropped atomic bombs on the Japanese cities of Hiroshima and Nagasaki.

Both wars involved significant human suffering and injustice. During World War I, chemical weapons were used despite international laws against them. The Ottoman Empire was responsible for the Armenian genocide. In World War II, Nazi Germany carried out the Holocaust. This resulted in the murder of about six million Jews and five million others. These victims included Slavs, Roma, and people with disabilities. Japan was also responsible for the Nanjing Massacre, where 250,000 civilians were killed.

The end of World War II changed the entire world structure. Old European empires collapsed due to high costs or military defeat. The United States and the Soviet Union emerged as dominant global superpowers. These two nations exerted political influence over most nation-states for decades. To prevent future wars, the United Nations was established to manage international affairs. Wartime research also led to peacetime breakthroughs. These included jet aircraft, penicillin, nuclear energy, and electronic computers.

Historians also debate if other wars should be called world wars. Some suggest the Seven Years' War (1756–1763) was "World War 0." It was fought across North America, Europe, Asia, Africa, and South America. Other historians list the Napoleonic Wars or the French Revolutionary Wars as global conflicts. Since the atomic age, there has been a widespread fear of a third world war. Many worry a third war would be a nuclear conflict. Some leaders have even used labels like "World War IV" to describe more recent global tensions.