The First Transjordan attack on Amman by units of the Egyptian Expeditionary Force begins, with the passage of the Jordan River. March 23 WWI: The giant German cannon, the 'Paris Gun' (Kaiser Wilhelm Geschütz), begins to shell Paris from away. In London at the Wood Green Empire, Chung Ling Soo (William E. Robinson, U.S.-born magician) dies during his trick, where he is supposed to "catch" two separate bullets (but one of them perforates his lung). He dies the following morning in a hospital. March 25 The Belarusian People's Republic declares independence. Dr. Karl Muck, music director of the Boston Symphony Orchestra, is arrested under the Alien Enemies Act, and imprisoned for the duration of WWI. March 26 – Dr. Marie Stopes publishes her influential book Married Love in the U.K. March 27 – WWI: The First Battle of Amman is launched by units of the Egyptian Expeditionary Force, during the First Transjordan attack on Amman; it ends with their withdrawal on 31 March, back to the Jordan Valley. March 30 – March Days: Bolshevik and Armenian Revolutionary Federation forces suppress a Muslim revolt in Baku, Azerbaijan, resulting in up to 30,000 deaths. April April 1 – The Royal Flying Corps and the Royal Naval Air Service in Britain are merged to form the Royal Air Force, the first autonomous Air Force in the world. April 5 – Sālote succeeds as Queen of Tonga; she will remain on the throne until her death in 1965. April 6 – Finnish Civil War: The battle of Tampere ends. April 8 – Operations against the Marri and Khetran tribes in Balochistan end with surrender to the British authorities. April 9 – Union of Bessarabia with Romania: Bessarabia votes to become part of the Kingdom of Romania. April 21 – WWI: Manfred von Richthofen, "The Red Baron", the war's most successful fighter pilot, dies in combat at Morlancourt Ridge near the Somme River. April 22 – Armenia, Azerbaijan, and Georgia declare their independence from Russia as the Transcaucasian Democratic Federative Republic. April 23 – WWI: Conscription Crisis of 1918 in Ireland: A general strike is held here against conscription. Zeebrugge Raid: The British Royal Navy attempts to seal off the German U-boat base here. First Ostend Raid: The British Royal Navy unsuccessfully attempts to seal off the German U-boat base here. April 28 – WWI: Gavrilo Princip, assassin of Archduke Franz Ferdinand of Austria, dies