What happened in 1900

39 events　World 9, North America 6, Europe 12, Asia 2, Africa 10

Highlights of 1900

Jan 6AfricaSecond Boer War: Boers attempt to end the Siege of Ladysmith, which leads to the Battle of Platrand.
Jan 14North AmericaThe U.S. Senate accepts the British-German Treaty of 1899, in which the United Kingdom renounces its claims to the American Samoa portion of the Samoan Islands.
Jan 27WorldBoxer Rebellion: Foreign diplomats in Peking, Qing dynasty China, demand that the Boxer rebels (who oppose foreign interests in the country) be disciplined.
Mar 23WorldKarl 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.
Sep 13AsiaPhilippine–American War: Battle of Pulang Lupa – Filipino troops under Maximo Abad defeat a detachment of American soldiers.
Oct 19EuropeMax Planck first states Planck's law of black-body radiation to a meeting of the German Physical Society in Berlin, marking the birth of modern quantum mechanics. He restates it on December 14.

Jan 27Boxer Rebellion: Foreign diplomats in Peking, Qing dynasty China, demand that the Boxer rebels (who oppose foreign interests in the country) be disciplined.
Mar 23Karl 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.
May 17Boxer Rebellion: Boxers destroy three villages near Peking and kill 60 Chinese Christians.
May 28Boxer Rebellion: Boxers attack Belgians in the Fengtai railway station.
May 31Boxer Rebellion: Peacekeepers from various European countries arrive in China, where they eventually unite with Japanese forces.
Jun 17Boxer Rebellion: Battle of Dagu Forts – Naval forces of the Eight-Nation Alliance capture the Taku Forts, on the Hai River estuary in China.
Jun 20Boxer Rebellion: Boxers gather about 20,000 people near Peking, and kill hundreds of European citizens, including the German ambassador.
Aug 14Boxer Rebellion: An international contingent of troops, under British command, invades Peking and frees the European hostages.
Dec 24Boxer Rebellion Demands: The foreign powers present their 12 conditions for reform to the Chinese Imperial government, including the payment of a large indemnity.

Jan 2U.S. Secretary of State John Hay announces the Open Door Policy to promote American trade with China.
Jan 14The U.S. Senate accepts the British-German Treaty of 1899, in which the United Kingdom renounces its claims to the American Samoa portion of the Samoan Islands.
Apr 30Casey Jones dies in fatal train accident after his locomotive, No. 382, plows into the caboose and two fully loaded boxcars of corn and hay of locomotive No. 83.
May 1Scofield Mine disaster: An explosion of blasting powder in a coal mine in Scofield, Utah, kills 200 people.
May 17L. 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.
Nov 61900 United States presidential election: Republican incumbent William McKinley is re-elected by defeating Democratic challenger William Jennings Bryan in a rematch.

Jan 14Puccini's opera Tosca premieres in Rome.
Janc. January – The first Michelin Guide is published for French motorists.
Feb 27The British Labour Party is officially established, at a meeting in the Congregational Memorial Hall in London, and Ramsay MacDonald is appointed as its first secretary.
Apr 14The Exposition Universelle, a world's fair, opens in Paris.
May 14The second Olympic Games, Paris 1900, open (as part of the Paris World Exhibition).
Jul 2The first zeppelin airship flight, by Zeppelin LZ 1, is carried out over Lake Constance, near Friedrichshafen, Germany.
Jul 19The first line of the Paris Metro opens.
Jul 23The First Pan-African Conference is held in London.
Jul 29King Umberto I of Italy is assassinated by Italian-born anarchist Gaetano Bresci in Monza.
Oct 19Max Planck first states Planck's law of black-body radiation to a meeting of the German Physical Society in Berlin, marking the birth of modern quantum mechanics. He restates it on December 14.
Dec 5The final Anglo-Ashanti War, "War of the Golden Stool", is declared over. Most of the British troops and Governor James Willcocks depart the city of Kumasi.
Dec 14History of quantum mechanics: Max Planck presents his groundbreaking paper on quantum theory to the German Physical Society in Berlin.

Sep 13Philippine–American War: Battle of Pulang Lupa – Filipino troops under Maximo Abad defeat a detachment of American soldiers.
Sep 17Philippine–American War: Battle of Mabitac – Filipinos under Juan Cailles defeat the Americans.

Jan 6Second Boer War: Boers attempt to end the Siege of Ladysmith, which leads to the Battle of Platrand.
Jan 24Second Boer War: Battle of Spion Kop – Boer troops defeat the British Army.
Feb 8Second Boer War: British troops defeat the Boers at Ladysmith, South Africa.
Feb 15Second Boer War: The Siege of Kimberley is lifted.
Feb 17Second Boer War: Battle of Paardeberg – British troops defeat the Boers.
Feb 27Second Boer War: British military leaders accept the unconditional notice of surrender from Boer General Piet Cronjé.
Apr 22Battle of Kousséri: French forces secure their domination of Chad. Warlord Rabih az-Zubayr is defeated and killed.
May 17Second Boer War: The British Army relieves the Siege of Mafeking.
May 24Second Boer War: The British annex the Orange Free State, as the Orange River Colony.
Jun 5Second Boer War: British soldiers take Pretoria.