World War II, which spanned from 1939 to 1945, was a global conflict that engaged nearly all the world's nations and led to significant political, social, and economic changes. This war was primarily fought between two major alliances: the Allies and the Axis powers. The complexities of this conflict stemmed from unresolved tensions following World War I, the rise of fascism in Europe, and militarism in Japan. The war is generally recognized to have commenced on September 1, 1939, when Nazi Germany, led by Adolf Hitler, invaded Poland. This invasion prompted the United Kingdom and France to declare war on Germany shortly thereafter. The war rapidly expanded, with Japan attacking American and British territories in December 1941, marking its formal engagement in the broader conflict that became World War II. The war saw significant battles and campaigns across various fronts, including Europe, the Pacific, and North Africa. World War II was unprecedented in scale and brutality, resulting in the deaths of approximately 70 to 85 million people, with civilians making up more than half of the casualties. The Holocaust, wherein millions of Jews and other marginalized groups were systematically exterminated, represents one of the darkest chapters of this conflict. In addition to genocides, numerous others perished from massacres, starvation, and disease in wartime. Key events such as the German invasion of the Soviet Union in 1941 and Japan's military aggressions in Southeast Asia profoundly influenced the direction of the war. The turning points came in 1942 and 1943 with major defeats for the Axis powers, particularly the significant battles at Stalingrad and Midway. By 1944, the tide had decisively turned in favor of the Allies, leading to the liberation of occupied territories in Europe and the eventual surrender of Axis powers. The conclusion of the war on September 2, 1945, followed a series of dramatic events, including the Allied invasions of Nazi-occupied territories and the use of nuclear weapons by the United States on the Japanese cities of Hiroshima and Nagasaki. These bombings prompted Japan to surrender unconditionally, effectively bringing an end to the war. The aftermath of World War II reshaped international relations and established the groundwork for modern geopolitics. The formation of the United Nations aimed to foster international cooperation and prevent future global conflicts. The Soviet Union and the United States emerged as superpowers, initiating a period known as the Cold War characterized by political tensions and military rivalry. Meanwhile, Europe faced a rebuilding phase marked by the decolonization of Africa and Asia as nations sought self-determination in the wake of colonial rule. In conclusion, World War II was a monumental event that not only altered national boundaries and power structures but also had lasting effects on society and politics worldwide. The legacy of the war reminds us of the devastating consequences of global conflict and the importance of diplomacy and cooperation among nations to ensure peace.[1][2][3][4][5]

• 1 September 1939World War II begins when Nazi Germany invades Poland.
• 3 September 1939The United Kingdom and France declare war on Germany.
• 1940The Soviet Union annexes the Baltic states and parts of Finland and Romania.