1928January 1928 January – British bacteriologist Frederick Griffith reports the results of Griffith's experiment, indirectly proving the existence of DNA. January 1 – Eastern Bloc emigration and defection: Boris Bazhanov, Joseph Stalin's personal secretary, crosses the border to Iran to defect from the Soviet Union. January 17 – The OGPU arrests Leon Trotsky in Moscow; he assumes a status of passive resistance and is exiled with his family. January 26 – The volcanic island Anak Krakatau appears.
1922January 1922 January 7 – Dáil Éireann, the parliament of the Irish Republic, ratifies the Anglo-Irish Treaty by 64–57 votes. January 10 – Arthur Griffith is elected President of Dáil Éireann, the day after Éamon de Valera resigns. January 11 – The first successful insulin treatment of diabetes is made, by Frederick Banting in Toronto. January 15 – Michael Collins becomes Chairman of the Provisional Government of the Irish Free State. January 26 – Italian forces occupy Misrata, Libya; the reconquest of Libya begins.
1936January 1936 February 1936 January 20 – George V, King of the United Kingdom and the British Dominions and Emperor of India, dies at his Sandringham Estate. The Prince of Wales succeeds to the throne of the United Kingdom as King Edward VIII. January 28 – State funeral of George V of the United Kingdom. After a procession through London, he is buried at St George's Chapel, Windsor Castle. February 4 – Radium E (bismuth-210) becomes the first radioactive element to be made synthetically.
1929This year marked the end of a period known in American history as the Roaring Twenties after the Wall Street Crash of 1929 ushered in a worldwide Great Depression. In the Americas, an agreement was brokered to end the Cristero War, a Catholic counter-revolution in Mexico. The Judicial Committee of the Privy Council, a British high court, ruled that Canadian women are persons in the Edwards v. Canada (Attorney General) case. The 1st Academy Awards for film were held in Los Angeles, while the Museum of Modern Art opened in New York City.
1961January 1961 January 3 United States President Dwight D. Eisenhower announces that the United States has severed diplomatic and consular relations with Cuba (Cuba–United States relations are restored in 2015). Aero Flight 311 (Koivulahti air disaster): Douglas DC-3C OH-LCC of Finnish airline Aero crashes near Kvevlax (Koivulahti), on approach to Vaasa Airport in Finland, killing all 25 on board, due to pilot error: an investigation finds that the captain and first officer were both exhausted for lack of sleep, and had consumed excessive amounts of alcohol at the time of the crash.
1931January 1931 January 2 – South Dakota native Ernest Lawrence invents the cyclotron, used to accelerate particles to study nuclear physics. January 4 – German pilot Elly Beinhorn begins her flight to Africa. January 22 – Sir Isaac Isaacs is sworn in as the first Australian-born Governor-General of Australia. January 25 – Mohandas Gandhi is again released from imprisonment in India. January 27 – Pierre Laval forms a government in France.
1924January 1924 January 12 – Gopinath Saha shoots Ernest Day, whom he has mistaken for Sir Charles Tegart, the police commissioner of Calcutta, and is arrested soon after. January 20–30 – Kuomintang in China holds its first National Congress, initiating a policy of alliance with the Soviet Union and the Chinese Communist Party. January 21 – The Earl of Athlone is appointed Governor-General of the Union of South Africa, and High Commissioner for Southern Africa. January 22 – Ramsay MacDonald becomes the first Labour Prime Minister of the United Kingdom.
1943Below, the events of World War II have the "WWII" prefix. January 1943 January 1 – WWII: The Soviet Union announces that 22 German divisions have been encircled at Stalingrad, with 175,000 killed and 137,650 captured. January 4 – WWII: Greek-Polish athlete and saboteur Jerzy Iwanow-Szajnowicz is executed by the Germans at Kaisariani. January 10 – WWII: Guadalcanal Campaign: American forces of the 2nd Marine Division and the 25th Infantry Division begin their assaults on the Galloping Horse and Sea Horse on Guadalcanal.
1919January 1919 January 1 The Czechoslovak Legions occupy much of the self-proclaimed "free city" of Pressburg (now Bratislava), enforcing its incorporation into the new republic of Czechoslovakia. HMY Iolaire sinks off the coast of the Hebrides; 201 people, mostly servicemen returning home to Lewis and Harris, are killed. January 2–22 – Russian Civil War: The Red Army's Caspian-Caucasian Front begins the Northern Caucasus Operation against the White Army, but fails to make progress.
1900As of March 1 (O.S. February 17), when the Julian calendar acknowledged a leap day and the Gregorian calendar did not, the Julian calendar fell one day further behind, bringing the difference to 13 days until February 28 (O.S. February 15), 2100. The year 1900 also marked the Year of the Rat on the Chinese calendar. January 1900 January 2 – U.S. Secretary of State John Hay announces the Open Door Policy, to promote American trade with China. January 3 – The United States Census estimates the country's population to be about 70 million people.