World War II

World War II, or the Second World War, (often called WWII or WW2) was a global military conflict which involved a majority of the world's nations, including all of the great powers. The war involved the mobilisation of over 100 million military personnel, making it the biggest war in history. In a state of "total war", the major participants placed their complete economic, industrial, and scientific capabilities at the service of the war effort, erasing the different between civilian and military resources. Over seventy million people, the majority of them civilians, were killed, making it the deadliest conflict in human history.

The start of the war is generally held to be in September 1939 with the German invasion of Poland and subsequent declarations of war on Nazi Germany by the British Commonwealth and France.Many belligerents entered the war before or after this date, during a period which spanned from 1937 to 1941, as a result of other events. Amongst these main events are the Marco Polo Bridge Incident (fought between Nationalist China and Japan), the start of Operation Barbarossa (the Nazi invasion of Russia), and the attacks on Pearl Harbor and British and Dutch colonies in South East Asia.

The Soviet Union and the United States emerged from the war as the world's superpowers. This set the stage for the Cold War, which lasted for the next 45 years. The United Nations was formed in the hope of preventing another such conflict. The self-determination spawned by the war accelerated decolonisation movements in Asia and Africa, while Western Europe itself began moving toward integration.

World War 1

The First World War, also known as the Great War, was a world conflict occurring from 1914 to 1918. No previous conflict had mobilized so many soldiers or involved so many in the field of battle. Never before had casualties been so high. Chemical weapons were used for the first time, the first mass bombardment of civilians from the sky was executed, and some of the century's first large-scale civilian massacres took place. Four dynasties, the Habsburgs, the Romanovs, the Ottomans and the Hohenzollerns, who had roots of power back to the days of the Crusades, all fell after the war.

World War I proved to be the decisive break with the old world order, marking the final demise of absolutist monarchy in Europe. It would prove the catalyst for the Russian Revolution, which would inspire later revolutions in countries as diverse as China and Cuba, and would lay the basis for the Cold War standoff between the Soviet Union and the United States. The defeat of Germany in the war and failure to resolve the unsettled issues that had caused the Great War would lay the basis for the rise of Nazism, and thus the outbreak of World War II in 1939. It also laid the basis for a new form of warfare that relied heavily on technology, and would involve non-combatants in war as never before.World War I became infamous for trench warfare, where huge numbers of troops were confined to trenches and could move little because of tight defenses. This was especially true of the Western Front. Over 9 million died on the battlefield, and nearly that many more on the home front due to food shortages, genocide, and ground combat.