World War II was a global conflict that lasted from 1939 to 1945, involving most of the world's nations. The war began in September 1939 when Germany, led by Adolf Hitler, invaded Poland. This act of aggression prompted the United Kingdom and France to declare war on Germany, marking the beginning of the conflict.
The roots of World War II can be traced back to the Treaty of Versailles, which ended World War I. The treaty imposed harsh penalties on Germany, leading to widespread resentment among the German people. This created an environment in which extremist ideologies like Nazism could flourish.
As the war progressed, Germany's aggression continued unabated. In 1941, Germany launched a surprise attack on the Soviet Union, known as Operation Barbarossa. This led to a prolonged and bloody conflict that lasted for four years.
Meanwhile, Japan had been secretly building its military presence in Asia, culminating in the surprise attack on Pearl Harbor in December 1941. The United States entered the war after this event, shifting the balance of power in favor of the Allies.
The tide of the war began to turn in favor of the Allies after the successful invasion of Normandy on June 6, 1944. This pivotal moment marked a significant shift in momentum, as Allied forces gained a foothold in Western Europe.
In the Pacific Theater, the United States and its allies were making steady progress against Japan. The atomic bombings of Hiroshima and Nagasaki in August 1945 brought an abrupt end to the war, as Japan surrendered unconditionally.