World Events
- Churchill becomes Prime Minister of the United Kingdom.
- Germany invades Denmark, Norway, Belgium, the Netherlands, Luxembourg and France. The Nazis warn that listening to foreign radio is an offence punishable by death.
- The Dunkirk evacuation: 299 British warships and 420 other vessels under constant attack evacuate 335,490 British and French troops.
- Italy declares war on Britain and France.
- Germany, Japan and Italy sign an economic and military pact.
- Germany launches a bombing blitz against Britain.
- Battle of Britain: the RAF prevent a German invasion of Britain.
- Italy invades Greece.
- Japan invades French Indo-China.
- Blood plasma is first used in blood transfusions.