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On May 10, 1994, Nelson Mandela was inaugurated as President of South Africa at the Union Buildings in Pretoria, in what was the first presidential inauguration in which citizens of all races participated. Mandela, who had spent 27 years in prison, promised a Rainbow South Africa — a term coined by Archbishop Desmond Tutu — where all races and cultures would live together in peace.

On May 10, 1869, the last stretch of the American Transcontinental Railroad was completed with the famous "Golden Spike" at Promontory Summit, Utah, connecting the East and West coasts of the US with 3,000 km of track. The work, built in 6 years by 20,000 Chinese and Irish workers, transformed the country by reducing the journey from New York to San Francisco from 6 months to 6 days and accelerated Western settlement.

On May 10, 1940, Germany launched the Western Offensive, simultaneously invading France, Belgium, Netherlands and Luxembourg — the fastest and most devastating military operation in modern history up to that point. That same day, Winston Churchill was appointed Prime Minister of the United Kingdom, replacing Neville Chamberlain. Within six weeks, the entire western continental Europe would fall under Nazi control.