MacDonald is appointed as its first secretary. Second Boer War: British military leaders accept the unconditional notice of surrender from Boer General Piet Cronjé. FC Bayern, Germany's most successful football club, is founded in Munich. March March 5 – Two U.S. Navy cruisers are sent to Central America to protect American interests in a dispute between Nicaragua and Costa Rica. March 6 – A coal mine explosion in West Virginia, United States, kills 50 miners. March 14 Botanist Hugo de Vries rediscovers Mendel's Laws of Heredity. The Gold Standard Act is ratified, placing the United States currency on the gold standard. March 16 – British archaeologist Sir Arthur Evans purchases the land on Crete on which the ruins of the Palace of Knossos stand. He begins to unearth some of the palace three days later. March 18 – AFC Ajax, a successful football club in Netherlands, is founded in Amsterdam. March 23 – Dr. Karl Landsteiner first reports his discovery of an accurate means for classifying a system of blood type, which will universally be referred to as the ABO blood group system and for which he will be awarded the Nobel Prize in Physiology or Medicine in 1930. March 27 – The arrival of a Russian naval fleet in Korea causes concern to the Imperial Japanese government. April April 14 – The Exposition Universelle, a world's fair, opens in Paris. April 22 – Battle of Kousséri: French forces secure their domination of Chad. Warlord Rabih az-Zubayr is defeated and killed. May May – American explorer Robert Peary is the first person to sight Kaffeklubben Island. May 1 – Scofield Mine disaster: An explosion of blasting powder in a coal mine in Scofield, Utah, United States, kills 200 people. May 14 – The second Olympic Games, Paris 1900, open (as part of the Paris World Exhibition). May 17 Second Boer War: The British Army relieves the Siege of Mafeking. Boxer Rebellion: Boxers destroy three villages near Peking, and kill 60 Chinese Christians. L. Frank Baum's The Wonderful Wizard of Oz is published in Chicago, the first of Baum's Oz books, chronicling the fictional Land of Oz for children. May 18 – The United Kingdom proclaims a protectorate over Tonga. May 21 – Russia invades Manchuria. May 24 – Second Boer War: The British annex the Orange Free State, as the Orange River Colony. May 28 – Boxer Rebellion: The Boxers