The Gregorian calendar reforms took place. (1582) The majority of the world was operating on the Julian calendar at the time, which was inaccurate enough to cause a disparity between the seasons and the dates. Many countries changed over to the Gregorian calendar in the Middle Ages, although both Russia and Greece still used the Julian calendar until the 20th century.
US President Andrew Johnson was impeached. (1868) The House of Representatives voted 11 articles of impeachment against Johnson, and he missed being impeached by the Senate by a single vote. He was charged with violating the Tenure of Office Act, and was the first president to be impeached in the history of the US.
The Battle of Los Angeles occurred. (1942) Rumors of an enemy attack on Los Angeles spiraled out of control when authorities ordered a full black out of the city and began a major anti-aircraft artillery barrage. The incident was later deemed to be a false alarm, though it is still surrounded by conspiracy theories.
The Zimmerman Note was presented to a US ambassador. (1917) British authorities had intercepted and decoded the Zimmerman Note, a message from Nazi Germany to Mexico asking them to side with the Axis. The discovery of the note had a major impact on the previously negative public opinion towards getting involved in the war, and the US formally declared war against Germany four days later.
National Public Radio (NPR) was founded. (1970) The popular public radio station was created by Congressional mandate, along with the Corporation for Public Broadcasting. Its programs "Morning Edition" and "All Things Considered" rank among the most popular radio programs in America.
The Nazi Party was officially founded. (1920) On this day, the German Workers' Party (DAP) became the National Socialist German Worker's Party (NADAP) or Nazis. At the time, Adolf Hitler was a relatively minor member of the party, but quickly rose to power because of his charisma and oratory skills.
The concept of judicial review was established. (1803)Judicial review — the idea that the Supreme Court has the power to mandate whether an act of Congress is constitutional or not — was first established on this day in the case Marbury v. Madison. One of the main opponents of the idea was Thomas Jefferson.
The Food and Drug Administration (FDA) named six safe "morning after" pills. (1997) Before the FDA's approval, it was impossible to get emergency contraception without a doctor's help, and the pills were only supposed to be prescribed in the case of a rape.
The British royal family announced the engagement of Prince Charles and Lady Diana. (1981) Their relationship was the subject of intense scrutiny by the public, and was seen as a fairy tale romance by many in the beginning. Diana in particular remained a popular public figure after their divorce and even after her premature death in 1997.
The Gulf War ground offensive began. (1991) The ground invasion of Kuwait and Iraq was preceded by six weeks of bombing, and most of the Iraqi forces surrendered within a few days. Four days later there was a cease-fire, and the war officially ended.