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On March 15, 44 BC — the "Ides of March" — Roman dictator Julius Caesar was assassinated at the Theatre of Pompey in Rome by a group of senators led by Brutus and Cassius, who stabbed him 23 times. Caesar's death, coming as he was about to declare himself king, triggered the civil wars that ended the Roman Republic and led to the Empire under Augustus.

On March 15, 1917, Tsar Nicholas II of Russia abdicated in favour of his brother Michael, who renounced the throne the following day, ending 300 years of the Romanov dynasty. The abdication was the consequence of the February Revolution and military pressure. The provisional government that followed him would be overthrown eight months later by Lenin's Bolsheviks in the October Revolution.

On March 15, 1493, Christopher Columbus returned to Palos de la Frontera after his first voyage to the Americas, completing the most important voyage of discovery in modern history. The news spread rapidly across Europe, though Columbus died believing he had reached Asia. The return marked the beginning of the Spanish colonial period in America and the first globalisation in history.