March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. There are 280 days remaining until the end of the year.
- 590 – Emperor Maurice proclaims his son Theodosius as co-emperor of the Byzantine Empire.
- 908 – Emperor Zhu Wen of Later Liang has Li Zhu, the last Tang Dynasty emperor, poisoned.
- 1027 – Pope John XIX crowns Conrad II as Holy Roman Emperor.
- 1169 – Saladin becomes the emir of Egypt.
- 1344 – The Siege of Algeciras, one of the first European military engagements where gunpowder was used, comes to an end.
- 1351 – Combat of the Thirty: Thirty Breton knights call out and defeat thirty English knights.
- 1484 – William Caxton prints his translation of Aesop's Fables.
- 1552 – Guru Amar Das becomes the Third Sikh guru.
- 1636 – Utrecht University is founded in the Netherlands.
- 1812 – An earthquake devastates Caracas, Venezuela.
- 1812 – A political cartoon in the Boston Gazette coins the term "gerrymander" to describe oddly shaped electoral districts designed to help incumbents win reelection.
- 1830 – The Book of Mormon is published in Palmyra, New York.
- 1839 – The first Henley Royal Regatta is held.
- 1871 – The elections of Commune council of the Paris Commune are held.
- 1885 – The Métis people of the District of Saskatchewan under Louis Riel begin the North-West Rebellion against Canada.
- 1913 – First Balkan War: Bulgarian forces capture Adrianople.
- 1915 – The Vancouver Millionaires win the 1915 Stanley Cup Finals, the first championship played between the Pacific Coast Hockey Association and the National Hockey Association.
- 1917 – World War I: First Battle of Gaza: British troops are halted after 17,000 Turks block their advance.
- 1922 – The German Social Democratic Party is founded in Poland.
- 1931 – Swissair is founded as the national airline of Switzerland.
- 1931 – Ho Chi Minh Communist Youth Union is founded in Vietnam.
- 1934 – The United Kingdom driving test is introduced.
- 1939 – Spanish Civil War: Nationalists begin their final offensive of the war.
- 1942 – World War II: The first female prisoners arrive at Auschwitz concentration camp in German-occupied Poland.
- 1945 – World War II: The Battle of Iwo Jima ends as the island is officially secured by American forces.
- 1954 – Nuclear weapons testing: The Romeo shot of Operation Castle is detonated at Bikini Atoll. Yield: 11 megatons.
- 1958 – The United States Army launches Explorer 3.
- 1958 – The African Regroupment Party is launched at a meeting in Paris.
- 1967 – Ten thousand people gather for one of many Central Park be-ins in New York City.
- 1970 – South Vietnamese President Nguyễn Văn Thiệu implements a land reform program to solve the problem of land tenancy
- 1971 – East Pakistan declares its independence from Pakistan to form Bangladesh and the Bangladesh Liberation War begins.
- 1975 – The Biological Weapons Convention comes into force.
- 1979 – Anwar al-Sadat, Menachem Begin and Jimmy Carter sign the Egypt–Israel Peace Treaty in Washington, D.C.
- 1981 – Social Democratic Party (UK) is founded as a party.
- 1982 – A groundbreaking ceremony for the Vietnam Veterans Memorial is held in Washington, D.C..
- 1991 – Argentina, Brazil, Uruguay and Paraguay sign the Treaty of Asunción, establishing Mercosur, the South Common Market.
- 1997 – Thirty-nine bodies are found in the Heaven's Gate mass suicides.
- 1998 – During the Algerian Civil War, the Oued Bouaicha massacre sees fifty-two people, mostly infants, killed with axes and knives.
- 2005 – Around 200,000 to 300,000 Taiwanese demonstrate in Taipei in opposition to the Anti-Secession Law of China.
- 2010 – The South Korean Navy corvette Cheonan is torpedoed, killing 46 sailors. After an international investigation, the President of the United Nations Security Council blames North Korea.
- 2015 – Saudi Arabia begins its military intervention in Yemen , which led to deaths of thousands of people, many of whom were civilians.
- 2017 – Russia-wide anti-corruption protests in 99 cities. The Levada Center survey showed that 38% of surveyed Russians supported protests and that 67 percent held Putin personally responsible for high-level corruption.
