September 3, 1939

1939World War II: France, the United Kingdom, New Zealand and Australia declare war on Germany after the invasion of Poland, forming the Allied nations. The Viceroy of India also declares war, but without consulting the provincial legislatures.^[†]

World War II or the Second World War was a global conflict between two coalitions: the Allies and the Axis powers. Nearly all of the world's countries participated, with many nations mobilising all resources in pursuit of total war. Tanks and aircraft played major roles, enabling the strategic bombing of cities and delivery of the first and only nuclear weapons ever used in war. World War II is the deadliest conflict in history, causing the death of 70 to 85 million people, more than half of whom were civilians. Millions died in genocides, including the Holocaust, and by massacres, starvation, and disease. After the Allied victory, Germany, Austria, Japan, and Korea were occupied, and German and Japanese leaders were tried for war crimes.

1939World War II: The United Kingdom and France begin a naval blockade of Germany that lasts until the end of the war. This also marks the beginning of the Battle of the Atlantic.^[†]

The Blockade of Germany (1939–1945), also known as the Economic War, involved operations carried out during World War II by the British Empire and by France in order to restrict the supplies of minerals, fuel, metals, food and textiles needed by Nazi Germany – and later by Fascist Italy – in order to sustain their war efforts. The economic war consisted mainly of a naval blockade, which formed part of the wider Battle of the Atlantic, but also included the bombing of economically important targets and the preclusive buying of war materials from neutral countries in order to prevent their sale to the Axis powers.The first period, from the beginning of European hostilities in September 1939 to the end of the "Phoney War", saw both the Allies and the Axis powers intercepting neutral merchant ships to seize deliveries en route to their respective enemies. Naval blockade at this time proved less than effective because the Axis could get crucial materials from the Soviet Union until June 1941, while Berlin used harbours in Spain to import war materials into Germany. The second period began after the rapid Axis occupation of the majority of the European landmass in 1940–1941, resulting in Axis control of major centres of industry and agriculture. The third period started in December 1941 after the attack on Pearl Harbor by the Imperial Japanese Navy Air Service brought the U.S. officially into the European war. The final period came after the tide of war finally turned against the Axis after heavy military defeats up to and after D-Day in June 1944, which led to gradual Axis withdrawals from the occupied territories in the face of the overwhelming Allied military offensives.