| 70741 | June 21 | Event | 1582 – Sengoku period: Oda Nobunaga, the most powerful of the Japanese daimyo, was forced to commit suicide by his own general Akechi Mitsuhide. |
| 70742 | June 21 | Event | 1621 – Execution of 27 Czech noblemen on the Old Town Square in Prague as a consequence of the Battle of White Mountain. |
| 70743 | June 21 | Event | 1734 – In Montreal in New France, a slave known by the French name of Marie-Joseph Angélique is put to death, having been convicted of setting the fire that destroyed much of the city. |
| 70744 | June 21 | Event | 1749 – Halifax, Nova Scotia, is founded. |
| 70745 | June 21 | Event | 1768 – James Otis, Jr. offends the King and Parliament in a speech to the Massachusetts General Court. |
| 70746 | June 21 | Event | 1788 – New Hampshire ratifies the Constitution of the United States and is admitted as the ninth state in the United States. |
| 70747 | June 21 | Event | 1791 – King Louis XVI of France and his immediate family begin the Flight to Varennes during the French Revolution. |
| 70748 | June 21 | Event | 1798 – Irish Rebellion of 1798: The British Army defeats Irish rebels at the Battle of Vinegar Hill. |
| 70749 | June 21 | Event | 1813 – Peninsular War: Battle of Victoria. |
| 70750 | June 21 | Event | 1824 – Greek War of Independence: Egyptian forces capture Psara in the Aegean Sea. |
| 70751 | June 21 | Event | 1826 – Maniots defeat Egyptians under Ibrahim Pasha in the Battle of Vergas. |
| 70752 | June 21 | Event | 1848 – In the Wallachian Revolution, Ion Heliade Rădulescu and Christian Tell issue the Proclamation of Islaz and create a new republican government. |
| 70753 | June 21 | Event | 1854 – The first Victoria Cross is awarded during the bombardment of Bomarsund in the Åland Islands. |
| 70754 | June 21 | Event | 1864 – American Civil War: The Battle of Jerusalem Plank Road begins. |
| 70755 | June 21 | Event | 1864 – New Zealand land wars: The Tauranga Campaign ends. |
| 70756 | June 21 | Event | 1877 – The Molly Maguires, ten Irish immigrants convicted of murder, are hanged at the Schuylkill County and Carbon County, Pennsylvania prisons. |
| 70757 | June 21 | Event | 1898 – The United States captures Guam from Spain. |
| 70758 | June 21 | Event | 1900 – Boxer Rebellion. China formally declares war on the United States, Britain, Germany, France and Japan, as an edict issued from the Empress Dowager Cixi. |
| 70759 | June 21 | Event | 1915 – The U.S. Supreme Court hands down its decision in Guinn v. United States 238 US 347 1915, striking down an Oklahoma law denying the right to vote to some citizens. |
| 70760 | June 21 | Event | 1919 – The Royal Canadian Mounted Police fire a volley into a crowd of unemployed war veterans, killing two, during the Winnipeg General Strike. |
| 70761 | June 21 | Event | 1919 – Admiral Ludwig von Reuter scuttles the German fleet in Scapa Flow, Orkney. The nine sailors killed are the last casualties of World War I. |
| 70762 | June 21 | Event | 1929 – An agreement brokered by U.S. Ambassador Dwight Whitney Morrow ends the Cristero War in Mexico. |
| 70763 | June 21 | Event | 1930 – One-year conscription comes into force in France. |
| 70764 | June 21 | Event | 1940 – The first successful west-to-east navigation of Northwest Passage begins at Vancouver, British Columbia, Canada. |
| 70765 | June 21 | Event | 1942 – World War II: Tobruk falls to Italian and German forces. |
| 70766 | June 21 | Event | 1942 – World War II: A Japanese submarine surfaces near the Columbia River in Oregon, firing 17 shells at nearby Fort Stevens in one of only a handful of attacks by Japan against the United States mainland. |
| 70767 | June 21 | Event | 1945 – World War II: The Battle of Okinawa ends when the organized resistance of Imperial Japanese Army forces collapses in the Mabuni area on the southern tip of the main island. |
| 70768 | June 21 | Event | 1952 – The Philippine School of Commerce, through a republic act, is converted to Philippine College of Commerce, later to be the Polytechnic University of the Philippines. |
| 70769 | June 21 | Event | 1957 – Ellen Fairclough is sworn in as Canada's first female Cabinet Minister. |
| 70770 | June 21 | Event | 1963 – Cardinal Giovanni Battista Montini is elected as Pope Paul VI. |