1901–present 1908 – Natural Bridges National Monument is established in Utah. 1910 – The oldest existing indoor ice hockey arena still used for the sport in the 21st century, Boston Arena, opens for the first time. 1912 – Harriet Quimby becomes the first woman to fly an airplane across the English Channel. 1917 – Russian Revolution: Vladimir Lenin returns to Petrograd, Russia, from exile in Switzerland. 1919 – Mohandas Gandhi organizes a day of "prayer and fasting" in response to the killing of Indian protesters in the Jallianwala Bagh massacre by the British colonial troops three days earlier. 1919 – Polish–Lithuanian War: The Polish Army launches the Vilna offensive to capture Vilnius in modern Lithuania. 1922 – The Treaty of Rapallo, pursuant to which Germany and the Soviet Union re-establish diplomatic relations, is signed. 1925 – During the Communist St Nedelya Church assault in Sofia, Bulgaria, 150 are killed and 500 are wounded. 1941 – World War II: The Italian-German Tarigo convoy is attacked and destroyed by British ships. 1941 – World War II: The Nazi-affiliated Ustaše is put in charge of the Independent State of Croatia by the Axis powers after Operation 25 is effected. 1942 – King George VI awarded the George Cross to the people of Malta in appreciation of their heroism. 1943 – Albert Hofmann accidentally discovers the hallucinogenic effects of the research drug LSD. He intentionally takes the drug three days later on April 19. 1944 – World War II: Allied forces start bombing Belgrade, killing about 1,100 people. This bombing fell on the Orthodox Christian Easter. 1945 – World War II: The Red Army begins the final assault on German forces around Berlin, with nearly one million troops fighting in the Battle of the Seelow Heights. 1945 – The United States Army liberates Nazi Sonderlager (high security) prisoner-of-war camp Oflag IV-C (better known as Colditz). 1945 – More than 7,000 die when the German transport ship Goya is sunk by a Soviet submarine. 1947 – An explosion on board a freighter in port causes the city of Texas City, Texas, United States, to catch fire, killing almost 600 people. 1947 – Bernard Baruch first applies the term "Cold War" to describe the relationship between the United States and the Soviet Union. 1948 – The Organization of European Economic Co-operation is formed. 1961 – In a nationally broadcast speech, Cuban leader Fidel Castro declares that he is a Marxist–Leninist and that Cuba is going to adopt Communism. 1963 – U.S. civil rights campaigner Dr. Martin Luther King Jr. writes his open letter from Birmingham Jail, sometimes known as "The Negro Is Your Brother", while incarcerated in Birmingham, Alabama, for protesting against segregation. 1972 – Apollo program: The launch of Apollo 16 from Cape Canaveral, Florida. 2001 – India and Bangladesh begin a five-day border conflict, but are unable to resolve the disputes about their border. 2003 – The Treaty of Accession is signed in Athens admitting ten new member states to the European Union. 2007 – Virginia Tech shooting: Seung-Hui Cho guns down 32 people and injures 17 before committing suicide. 2008 – The U.S. Supreme Court rules in the Baze v. Rees decision that execution by lethal injection does not violate the Eighth Amendment ban against cruel and unusual punishment. 2012 – The trial for Anders Behring Breivik, the perpetrator of the 2011 Norway attacks, begins in Oslo, Norway. 2012 – The Pulitzer Prize winners were announced, it was the first time since 1977 that no book won the Fiction Prize. 2013 – A 7.8-magnitude earthquake strikes Sistan and Baluchestan province, Iran, killing at least 35 people and injuring 117 others. 2013 – The 2013 Baga massacre is started when Boko Haram militants engage government soldiers in Baga. 2014 – The South Korean ferry MV Sewol capsizes and sinks near Jindo Island, killing 304 passengers and crew and leading to widespread criticism of the South Korean government, media, and shipping authorities. 2016 – Ecuador's worst earthquake in nearly 40 years kills 676 and injures more than 230,000. 2018 – The New York Times and the New Yorker win the Pulitzer Prize for Public Service for breaking news of the Harvey Weinstein sexual abuse scandal. 2024 – The historic Børsen in Copenhagen, Denmark, is severely damaged by a fire.
1901–present 1908 – Natural Bridges National Monument is established in Utah. 1910 – The oldest existing indoor ice hockey arena still used for the sport in the 21st century, Boston Arena, opens for the first time. 1912 – Harriet Quimby becomes the first woman to fly an airplane across the English Channel. 1917 – Russian Revolution: Vladimir Lenin returns to Petrograd Russia, from exile in Switzerland. 1919 – Mohandas Gandhi organizes a day of "prayer and fasting" in response to the killing of Indian protesters in the Jallianwala Bagh massacre by the British colonial troops three days earlier. 1919 – Polish–Lithuanian War: The Polish Army launches the Vilna offensive to capture Vilnius in modern Lithuania. 1922 – The Treaty of Rapallo, pursuant to which Germany and the Soviet Union re-establish diplomatic relations, is signed. 1925 – During the Communist St Nedelya Church assault in Sofia, Bulgaria, 150 are killed and 500 are wounded. 1941 – World War II: The Italian-German Tarigo convoy is attacked and destroyed by British ships. 1941 – World War II: The Nazi-affiliated Ustaše is put in charge of the Independent State of Croatia by the Axis powers after Operation 25 is effected. 1942 – King George VI awarded the George Cross to the people of Malta in appreciation of their heroism. 1943 – Albert Hofmann accidentally discovers the hallucinogenic effects of the research drug LSD. He intentionally takes the drug three days later on April 19. 1944 – World War II: Allied forces start bombing Belgrade, killing about 1,100 people. This bombing fell on the Orthodox Christian Easter. 1945 – World War II: The Red Army begins the final assault on German forces around Berlin, with nearly one million troops fighting in the Battle of the Seelow Heights. 1945 – The United States Army liberates Nazi Sonderlager (high security) prisoner-of-war camp Oflag IV-C (better known as Colditz). 1945 – More than 7,000 die when the German transport ship Goya is sunk by a Soviet submarine. 1947 – An explosion on board a freighter in port causes the city of Texas City, Texas, United States, to catch fire, killing almost 600 people. 1947 – Bernard Baruch first applies the term "Cold War" to describe the relationship between the United States and the Soviet Union 1948 – The Organization of European Economic Co-operation is formed. 1961 – In a nationally broadcast speech, Cuban leader Fidel Castro declares that he is a Marxist–Leninist and that Cuba is going to adopt Communism. 1963 – U.S. civil rights campaigner Dr. Martin Luther King Jr. writes his open letter from Birmingham Jail, sometimes known as "The Negro Is Your Brother", while incarcerated in Birmingham, Alabama, for protesting against segregation. 1972 – Apollo program: The launch of Apollo 16 from Cape Canaveral, Florida. 2001 – India and Bangladesh begin a five-day border conflict, but are unable to resolve the disputes about their border. 2003 – The Treaty of Accession is signed in Athens admitting ten new member states to the European Union. 2007 – Virginia Tech shooting: Seung-Hui Cho guns down 32 people and injures 17 before committing suicide. 2008 – The U.S. Supreme Court rules in the Baze v. Rees decision that execution by lethal injection does not violate the Eighth Amendment ban against cruel and unusual punishment. 2012 – The trial for Anders Behring Breivik, the perpetrator of the 2011 Norway attacks, begins in Oslo, Norway. 2012 – The Pulitzer Prize winners were announced, it was the first time since 1977 that no book won the Fiction Prize 2013 – A 7.8-magnitude earthquake strikes Sistan and Baluchestan province, Iran, killing at least 35 people and injuring 117 others. 2013 – The 2013 Baga massacre is started when Boko Haram militants engage government soldiers in Baga. 2014 – The South Korean ferry MV Sewol capsizes and sinks near Jindo Island, killing 304 passengers and crew and leading to widespread criticism of the South Korean government, media, and shipping authorities. 2016 – Ecuador's worst earthquake in nearly 40 years kills 676 and injures more than 230,000. 2018 – The New York Times and the New Yorker win the Pulitzer Prize for Public Service for breaking news of the Harvey Weinstein sexual abuse scandal. 2024 – The historic Børsen in Copenhagen, Denmark, is severely damaged by a fire.