1900 CE

A year defined by the Boxer Rebellion in China, the Paris Exposition showcasing a new century's ambitions, and Max Planck's quantum theory that would reshape the foundations of physics.

Geopolitics & Diplomacy

The Boxer Rebellion erupted in China as the Society of Righteous and Harmonious Fists attacked foreign nationals and Chinese Christians, prompting an international military response.
An eight-nation alliance of Austria-Hungary, France, Germany, Italy, Japan, Russia, the United Kingdom, and the United States intervened militarily in China to relieve the besieged legations in Beijing.
Kaiser Wilhelm II of Germany delivered the Hun speech on July 27, urging German troops departing for China to show no mercy, drawing international criticism.
The United States Secretary of State John Hay issued the Open Door Notes, calling on major powers to preserve equal trading rights in China and respect Chinese territorial integrity.
The Second Boer War continued in South Africa as British forces captured Pretoria in June and annexed the Transvaal, though Boer guerrilla resistance persisted.
The Kingdom of Italy signed a secret agreement with France recognizing French interests in Morocco in exchange for Italian freedom of action in Libya.
Hawaii became an organized territory of the United States on April 30, with Sanford Dole appointed as its first territorial governor.
The Buganda Agreement was signed on March 10 between the British government and the Kingdom of Buganda, formalizing British colonial control over Uganda.
Tonga became a British protectorate under a treaty of friendship signed on May 18, preserving the Tongan monarchy under British oversight.
The Commonwealth of Australia Constitution Act received royal assent on July 9, paving the way for the federation of Australia's six colonies into a single nation on January 1, 1901.

Conflict & Security

The Siege of the International Legations in Beijing lasted from June 20 to August 14, as Boxer rebels and Qing imperial troops besieged the foreign diplomatic quarter.
The eight-nation alliance captured Beijing on August 14, lifting the siege of the legations and forcing the Qing court to flee the capital.
British forces under Lord Roberts captured Johannesburg on May 31 and Pretoria on June 5 during the Second Boer War, bringing the Boer capitals under British control.
Boer commandos shifted to guerrilla warfare tactics after the fall of their capitals, launching raids against British supply lines and garrisons across South Africa.
The British introduced concentration camps in South Africa to deny Boer guerrillas civilian support, interning Boer women and children under harsh conditions.
The Battle of Paardeberg in February resulted in the surrender of Boer General Piet Cronje and approximately 4,000 Boer fighters to British forces.
The Ashanti War of the Golden Stool began in March when the British governor of the Gold Coast demanded the sacred Golden Stool of the Ashanti people, sparking an armed uprising.
Russian troops occupied Manchuria during the Boxer Rebellion, ostensibly to protect Russian interests, but retained control after the crisis ended.
Filipino guerrillas continued armed resistance against American occupation forces in the Philippine-American War, fighting across Luzon and the Visayas.
The Yaqui people in Mexico continued their resistance against the government of Porfirio Diaz, facing forced deportation from Sonora to henequen plantations in Yucatan.

Economy & Finance

The Gold Standard Act was signed into law by President McKinley on March 14, formally establishing gold as the sole basis for redeeming paper currency in the United States.
The Paris Exposition Universelle opened on April 14, attracting over 50 million visitors and showcasing industrial and technological achievements from 40 countries.
The Exposition Universelle featured the Grand Palais and the Petit Palais, permanent structures built for the fair that became lasting landmarks of Paris.
Andrew Carnegie's steel empire produced a record output, making the United States the world's leading steel manufacturer and setting the stage for the consolidation of the industry.
Germany's naval expansion accelerated with the passage of the Second Naval Law, doubling the planned size of the German fleet and intensifying the Anglo-German naval arms race.
Railroad expansion continued across the world, with major construction projects under way in Russia, Africa, and South America to connect remote regions to global markets.
The Foraker Act established a civilian government in Puerto Rico on April 12, creating a political and economic framework for the island as a U.S. territory.
Standard Oil controlled approximately 90 percent of American oil refining, drawing increasing public criticism as a monopoly.
British colonial investment in South Africa was disrupted by the ongoing Boer War, which drained significant resources from the British Treasury.
Rubber demand surged as the automobile and bicycle industries expanded, driving exploitation of rubber workers in the Congo Free State and the Amazon basin.

Technology & Infrastructure

The Paris Exposition showcased the moving sidewalk, escalators, diesel engines, talking films, and other new technologies to an international audience.
Count Ferdinand von Zeppelin launched the first rigid airship, the LZ 1, over Lake Constance in Germany on July 2, beginning the era of dirigible aviation.
The Browning automatic pistol was patented by John Moses Browning, introducing a semiautomatic handgun design that would influence firearms development for decades.
The first electric bus operated in New York City, foreshadowing the electrification of urban public transport.
The Paris Metro opened its first line on July 19, running from Porte Maillot to Porte de Vincennes to serve visitors at the Exposition Universelle.
Reginald Fessenden transmitted speech by radio for the first time on December 23 from Cobb Island, Maryland, though the signal quality was poor.
The Otis Elevator Company installed escalators at the Paris Exposition, introducing the moving stairway to a mass audience.
The Davis Cup international tennis competition was established, with the first matches held between the United States and the British Isles at the Longwood Cricket Club in Boston.
The paper clip was patented in its modern double-loop design, becoming a ubiquitous office supply.
The first trial runs of the Paris-Lyon automobile route demonstrated the growing practicality of long-distance automotive travel in Europe.

Science & Discovery

Max Planck presented his quantum hypothesis on December 14, proposing that energy is emitted in discrete packets called quanta, laying the foundation for quantum physics.
Sigmund Freud published The Interpretation of Dreams, arguing that dreams are a form of wish fulfillment and introducing his theory of the unconscious mind.
The Dutch botanist Hugo de Vries published the first volume of Die Mutationstheorie, proposing that new species arise through sudden large-scale mutations rather than gradual Darwinian selection.
The three-domain system of gamma, beta, and alpha radiation was clarified by studies at the Cavendish Laboratory, advancing understanding of radioactive decay.
Paul Villard discovered gamma rays while studying radiation emitted by radium, identifying a new and highly penetrating form of electromagnetic radiation.
The rediscovery of Gregor Mendel's laws of heredity was independently reported by Hugo de Vries, Carl Correns, and Erich von Tschermak, launching the modern science of genetics.
David Hilbert presented his famous list of 23 unsolved mathematical problems at the International Congress of Mathematicians in Paris on August 8, shaping the direction of mathematics for the century.
Archaeologist Arthur Evans began excavations at Knossos on Crete, uncovering the ruins of the Minoan Palace and revealing an ancient Bronze Age civilization.
Radon was identified as a radioactive element by Friedrich Ernst Dorn, who observed the emanation of a radioactive gas from radium.
The American astronomer James Keeler used the Crossley reflector at Lick Observatory to photograph thousands of nebulae, demonstrating that spiral nebulae were far more numerous than previously believed.

Health & Medicine

Walter Reed and the Yellow Fever Commission in Cuba confirmed that yellow fever was transmitted by the Aedes aegypti mosquito, validating Carlos Finlay's earlier hypothesis.
Major Walter Reed conducted controlled experiments at Camp Lazear in Cuba, using human volunteers to prove the mosquito transmission theory of yellow fever.
Jesse Lazear, a member of the Yellow Fever Commission, died on September 25 after being bitten by an infected mosquito during the research in Cuba.
Bubonic plague struck Sydney, Australia, prompting a major public health response including rat extermination campaigns and quarantine measures.
The Rockefeller Institute for Medical Research was established in New York City, becoming a leading center for biomedical research in the United States.
Malaria continued to be a major killer in tropical regions, with quinine remaining the only effective treatment available.
Tuberculosis was the leading cause of death in the United States and Europe, killing approximately one in seven people.
Sigmund Freud's publication of The Interpretation of Dreams introduced psychoanalysis as a method for treating mental illness through exploration of the unconscious.
Infant mortality rates remained extremely high worldwide, with approximately 15 to 20 percent of children in industrialized countries dying before their first birthday.
Aspirin, introduced by Bayer the previous year, became widely available commercially and rapidly grew into one of the most popular pain remedies in the world.

Climate & Environment

Atmospheric carbon dioxide concentration was approximately 296 parts per million, as later confirmed by ice core analysis.
The Galveston Hurricane struck Texas on September 8, killing an estimated 8,000 people and destroying most of the city, making it the deadliest natural disaster in United States history.
Severe flooding hit the state of Texas in the aftermath of the Galveston Hurricane, with storm surge reaching over 15 feet and inundating the island city.
Lacroix and other scientists continued monitoring volcanic activity in the Caribbean, noting increased fumarolic output on Mount Pelee in Martinique.
Deforestation accelerated across the tropics as European colonial powers expanded plantation agriculture in Africa, Southeast Asia, and the Pacific.
The Society for the Preservation of the Wild Fauna of the Empire was founded in Britain, one of the earliest international conservation organizations.
Severe drought conditions affected large parts of India, contributing to famine and crop failures in several provinces.
John Muir and the Sierra Club continued their campaign to establish new national parks and forest reserves in the western United States.
Svante Arrhenius published further work on the greenhouse effect, refining his 1896 calculations on how carbon dioxide in the atmosphere influences global temperatures.
Coal burning continued to accelerate worldwide as industrialization expanded, with Britain, Germany, and the United States as the largest emitters.

Culture & Society

The Paris Exposition Universelle drew over 50 million visitors and featured art, technology, and cultural exhibits from dozens of countries, celebrating the dawn of a new century.
The second modern Olympic Games were held in Paris from May 14 to October 28, with 997 athletes from 24 nations competing, including women for the first time.
L. Frank Baum published The Wonderful Wizard of Oz, which became one of the best-known works of American children's literature.
Joseph Conrad published Lord Jim, a novel exploring themes of honor, guilt, and redemption that became a landmark of English-language modernist literature.
Giacomo Puccini's opera Tosca premiered at the Teatro Costanzi in Rome on January 14, becoming one of the most performed operas in the repertoire.
The Associated Press was incorporated as a nonprofit news cooperative in New York, establishing itself as a major wire service.
The Cake Walk dance craze, originating in African American culture, gained widespread popularity in the United States and Europe.
The International Ladies' Garment Workers' Union was founded on June 3 in New York City, organizing women workers in the garment industry.
The world population was approximately 1.65 billion.
W.E.B. Du Bois attended the first Pan-African Conference in London in July, where delegates discussed the condition of people of African descent worldwide.