1900:
- Queen Victoria dies, and her son Edward VII ascends to the British throne.
- The Olympic Games are held in Paris for the second time.
- The German Empire annexes Alsace-Lorraine from France.
1901:
- The United Kingdom and the Netherlands sign the Treaty of London, which resolves a boundary dispute in Borneo.
- The Spanish-American War ends with the Treaty of Paris, resulting in the United States gaining control of Puerto Rico, Guam, and the Philippines from Spain.
1902:
- The Boer War ends with the Treaty of Vereeniging, granting South Africa independence from the British Empire.
- The Panama Canal Construction begins.
- The Asquith-Lloyd George Budget raises taxes on wealthy individuals and corporations, leading to the People's Budget Crisis in the UK.
1903:
- The Wright Brothers make the first powered, controlled airplane flight in Kitty Hawk, North Carolina.
- The Russian Social Democratic Labor Party (RSDLP) splits into two factions: the Bolsheviks, led by Vladimir Lenin, and the Mensheviks, led by Julius Martov.
- The Kingdom of Italy, the Austrian Empire, and the German Empire sign the Triple Alliance, a mutual defense pact.
1904:
- The Russo-Japanese War begins over territorial disputes in Manchuria and Korea.
- The construction of the Panama Canal is completed.
1905:
- The First Moroccan Crisis occurs when Germany challenges France's control over Morocco, leading to heightened tensions between the European powers.
- Albert Einstein publishes his theory of special relativity.
1906:
- The Algeciras Conference resolves the First Moroccan Crisis, reaffirming France's control over Morocco.
- The Russian Revolution of 1905 begins, sparked by the Bloody Sunday massacre.
1907:
- The Triple Entente is formed between the United Kingdom, France, and Russia, forming a loose alliance against Germany and Austria-Hungary.
- The Second Hague Peace Conference is held, aiming to further international peace and cooperation.
1908:
- Austria-Hungary annexes Bosnia and Herzegovina from the Ottoman Empire, leading to increased tensions in the Balkans.
- The Young Turk Revolution takes place in the Ottoman Empire, leading to the establishment of a constitutional monarchy.
1909:
- Louis Blériot becomes the first person to fly across the English Channel in an airplane.
- The first feature-length film, "The Story of the Kelly Gang," is released in Australia.
1910:
- The Portuguese First Republic is established after the overthrow of King Manuel II.
- Halley's Comet appears in the night sky, visible to observers around the world.