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, to catch fire, killing almost 600. 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 – Dr. Martin Luther King Jr. pens his Letter from Birmingham Jail while incarcerated in Birmingham, Alabama for protesting against segregation.