37 – Roman emperor Caligula accepts the titles of the Principate, entitled to him by the Senate. 193 – Roman Emperor Pertinax is assassinated by Praetorian Guards, who then sell the throne in an auction to Didius Julianus. 364 – Roman Emperor Valentinian I appoints his brother Flavius Valens co-emperor. 845 – Paris is sacked by Viking raiders, probably under Ragnar Lodbrok, who collects a huge ransom in exchange for leaving. 1566 – The foundation stone of Valletta, Malta's capital city, is laid by Jean Parisot de Valette, Grand Master of the Sovereign Military Order of Malta. 1776 – Juan Bautista de Anza finds the site for the Presidio of San Francisco. 1794 – Allies under Prince Josias of Saxe-Coburg-Saalfeld defeat French forces at Le Cateau. 1795 – Partitions of Poland: The Duchy of Courland and Semigallia, a northern fief of the Polish–Lithuanian Commonwealth, ceases to exist and becomes part of Imperial Russia. 1802 – Heinrich Wilhelm Matthäus Olbers discovers 2 Pallas, the second asteroid known to man. 1809 – Peninsular War: France defeats Spain in the Battle of Medellín. 1814 – War of 1812: The Royal Navy of the United Kingdom defeats the United States Navy in the Battle of Valparaiso, Chile. 1854 – Crimean War: France and Britain declare war on Russia. 1860 – First Taranaki War: The Battle of Waireka begins. 1862 – American Civil War: Battle of Glorieta Pass – in New Mexico, Union forces stop the Confederate invasion of New Mexico territory. The battle began on March 26. 1871 – The Paris Commune is formally established in Paris. 1883 – Tonkin Campaign: French victory in the Battle of Gia Cuc. 1889 – The Yngsjö murder in Yngsjö, Sweden: Anna Månsdotter is arrested along with her son. 1910 – Henri Fabre becomes the first person to fly a seaplane, the Fabre Hydravion, after taking off from a water runway near Martigues, France. 1913 – Guatemala becomes a signatory to the Buenos Aires copyright treaty. 1920 – Palm Sunday tornado outbreak of 1920 affects the Great Lakes region and Deep South states. 1933 – The Imperial Airways biplane City of Liverpool is believed to be the first airline lost to sabotage when a passenger sets a fire on board. 1939 – Spanish Civil War: Generalissimo Francisco Franco conquers Madrid after a three-year siege. 1941 – World War II: Battle of Cape Matapan – in the Mediterranean Sea, British Admiral Andrew Browne Cunningham leads the Royal Navy in the destruction of three major Italian heavy cruisers and two destroyers. 1942 – World War II: St Nazaire Raid: In occupied France, British naval forces successfully raid the German-occupied port of Saint-Nazaire. 1946 – Cold War: The United States State Department releases the Acheson–Lilienthal Report, outlining a plan for the international control of nuclear power. 1951 – First Indochina War: In the Battle of Mạo Khê, French Union forces, led by World War II hero Jean de Lattre de Tassigny, inflict a defeat on Việt Minh forces commanded by General Võ Nguyên Giáp. 1959 – The State Council of the People's Republic of China dissolves the government of Tibet. 1968 – Brazilian high school student Edson Luís de Lima Souto is shot by the police in a protest for cheaper meals at a restaurant for low-income students. The aftermath of his death is one of the first major events against the military dictatorship. 1969 – Greek poet and Nobel Prize laureate Giorgos Seferis makes a famous statement on the BBC World Service opposing the junta in Greece. 1970 – Gediz earthquake: A 7.2 magnitude earthquake strikes western Turkey at about 23:05 local time, killed 1,086 and injured 1,260. 1978 – The US Supreme Court hands down 5–3 decision in Stump v. Sparkman, 435 U.S. 349, a controversial case involving involuntary sterilization and judicial immunity. 1979 – A coolant leak at the Three Mile Island's Unit 2 nuclear reactor outside Harrisburg, Pennsylvania leads to the core overheating and a partial meltdown. 1979 – The British House of Commons passes a vote of no confidence against James Callaghan's government, precipitating a general election. 1990 – President George H. W. Bush posthumously awards Jesse Owens the Congressional Gold Medal. 1994 – In South Africa, Zulus and African National Congress supporters battle in central Johannesburg, resulting in 18 deaths. 1994 – BBC Radio 5 is closed and replaced with a new news and sport station BBC Radio 5 Live. 1999 – Kosovo War: Serb paramilitary and military forces kill 146 Kosovo Albanians in the Izbica massacre. 2000 – Three children are killed when a Murray County, Georgia, school bus is hit by a CSX freight train. 2003 – In a friendly fire incident, two A-10 Thunderbolt II attack aircraft from the United States Idaho Air National Guard's 190th Fighter Squadron attack British tanks participating in the 2003 invasion of Iraq, killing British soldier Matty Hull. 2005 – The 2005 Sumatra earthquake rocks Indonesia, and at magnitude 8.7 is the fourth strongest earthquake since 1965. 2006 – At least one million union members, students, and unemployed take to the streets in France in protest at the government's proposed First Employment Contract law.
- Sanders wins in Washington and Alaska
- Nigerian government set to verify “Chibok girl” claim by suspected suicide bomber