1910:
- The Mexican Revolution begins, lasting until 1920 and resulting in significant social, political, and cultural changes in Mexico.
- Halley's Comet becomes visible from Earth, attracting worldwide attention.
1911:
- The Chinese Revolution of 1911 overthrows the Qing dynasty and establishes the Republic of China, ending over 2,000 years of imperial rule.
- Marie Curie wins the Nobel Prize in Chemistry for her discovery of radium and polonium, becoming the first woman to receive two Nobel Prizes.
1912:
- The RMS Titanic, considered "unsinkable," hits an iceberg and sinks in the North Atlantic Ocean, resulting in the loss of over 1,500 lives.
- The Balkan Wars begin, involving several countries in the Balkans region and leading to significant territorial changes.
1913:
- The Federal Reserve System is established in the United States, creating a centralized banking system.
- The Armory Show, an important art exhibition in New York City, introduces modern European art to the American public.
1914:
- World War I begins, primarily centered in Europe but eventually involving countries worldwide.
- The Panama Canal opens, significantly reducing travel time between the Atlantic and Pacific Oceans.
1915:
- The Lusitania, a British passenger ship, is sunk by a German submarine, escalating tensions between the United States and Germany.
- Albert Einstein publishes his general theory of relativity, revolutionizing scientific understanding of gravity.
1916:
- The Battle of the Somme, one of the deadliest battles in World War I, results in millions of casualties.
- The Easter Rising, an uprising in Ireland, takes place, leading to increased support for Irish independence.
1917:
- The United States enters World War I, turning the tide in favor of the Allied Powers.
- The Russian Revolution begins, leading to the overthrow of the monarchy and the establishment of the Soviet Union.
1918:
- World War I ends with the signing of the Armistice, marking the defeat of Germany and its allies.
- The Spanish Flu pandemic spreads globally, infecting millions and causing widespread fatalities.
1919:
- The Treaty of Versailles is signed, officially ending World War I and placing severe restrictions on Germany.
- The League of Nations is established as an international organization to promote peace and cooperation.
- The Prohibition era begins in the United States, prohibiting the sale, manufacture, and transportation of alcoholic beverages.