World War II: Fascist Italy declares war on France and the United Kingdom, beginning an invasion of southern France.

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.

The Kingdom of Italy was governed by the National Fascist Party from 1922 to 1943 with Benito Mussolini as prime minister transforming the country into a totalitarian dictatorship. The Fascists crushed political opposition, while promoting economic modernization, traditional social values and a rapprochement with the Roman Catholic Church.

The Italian invasion of France, also called the Battle of the Alps, was the first major Italian engagement of World War II and the last major engagement of the Battle of France.

June 10 is the 161st day of the year in the Gregorian calendar; 204 days remain until the end of the year.