2016: Nagorno-Karabakh clashes: The Four Day War or April War, began along the Nagorno-Karabakh line of contact on April 1.
2011: After protests against the burning of the Quran turn violent, a mob attacks a United Nations compound in Mazar-i-Sharif, Afghanistan, resulting in the deaths of thirteen people, including eight foreign workers.
1970: President Richard Nixon signs the Public Health Cigarette Smoking Act into law, requiring the Surgeon General's warnings on tobacco products and banning cigarette advertising on television and radio in the United States, effective 1 January 1971.
1960: The TIROS-1 satellite transmits the first television picture from space.
1955: The EOKA rebellion against the British Empire begins in Cyprus, with the goal of unifying with Greece.
1949: Chinese Civil War: The Chinese Communist Party holds unsuccessful peace talks with the Nationalist Party in Beijing, after three years of fighting.
1946: The 8.6 Mw Aleutian Islands earthquake shakes the Aleutian Islands with a maximum Mercalli intensity of VI (Strong). A destructive tsunami reaches the Hawaiian Islands resulting in dozens of deaths, mostly in Hilo, Hawaii.
1939: Spanish Civil War: Generalísimo Francisco Franco of the Spanish State announces the end of the Spanish Civil War, when the last of the Republican forces surrender.
1933: The recently elected Nazis under Julius Streicher organize a one-day boycott of all Jewish-owned businesses in Germany, ushering in a series of anti-Semitic acts.
1833: The Convention of 1833, a political gathering of settlers in Mexican Texas to help draft a series of petitions to the Mexican government, begins in San Felipe de Austin
1826: Samuel Morey received a patent for a compressionless "Gas or Vapor Engine".
528: The daughter of Emperor Xiaoming of Northern Wei was made the "Emperor" as a male heir of the late emperor by Empress Dowager Hu, deposed and replaced by Yuan Zhao the next day; she was the first female monarch in the History of China, but not widely recognised.
457: Majorian is acclaimed emperor by the Roman army after defeating 900 Alemanni near Lake Maggiore (Italy).
325: Crown Prince Jin Chengdi, age 4, succeeds his father Jin Mingdi as emperor of the Eastern Jin dynasty.
286: Emperor Diocletian elevates his general Maximian to co-emperor with the rank of Augustus and gives him control over the Western regions of the Roman Empire.