On this day, June 20: Turks occupied Smederevo, Clara Zetkin died

June 20th marks a significant date in history, notably the fall of Smederevo to the Ottoman Turks in 1459. This event signified the formal end of the Serbian medieval state's independence, bringing it under the dominion of the Ottoman Empire.

Further historical milestones punctuate this date. In 1597, Dutch polar explorer Willem Barentsz died while attempting to find a northeastern sea passage. His name is now associated with the Barents Sea. A tragic event occurred in 1756 when 123 of 146 British soldiers died from suffocation in a prison cell in Calcutta, an incident that later became known as the "Black Hole of Calcutta."

The day also commemorates pivotal moments leading to revolutions and cultural contributions. In 1789, deputies of the Third Estate in France took an oath not to disband until a new constitution was established, a key precursor to the French Revolution. The birth of French composer Jacques Offenbach, known for operettas like "Orpheus in the Underworld," occurred in 1819. Coincidentally, the first steamship to cross the Atlantic, the "Savannah," arrived in Liverpool in the same year.

Significant figures also departed on this day. French revolutionary Abbé Sieyès, a key figure in the French Revolution and Napoleon's rise to power, died in 1836. British King William IV died in 1837, succeeded by Queen Victoria. The influential German revolutionary Clara Zetkin, who championed the international workers' movement and proposed March 8th as International Women's Day, died in 1933. The day also saw the birth of acclaimed actress Lilian Hellman in 1905 and the assassination of Mexican revolutionary Pancho Villa in 1923.