1973 (MCMLXXIII) in the Gregorian calendar was a year without a shooting day that began on a Monday.
Internet: First international connection to ARPANET: NORSAR, in Norway and London.
The Nazi organization "Nasjonal Ungdomsfylking" (later the Norwegian Front) is founded.
January 1st -
Denmark, Great Britain and Ireland become members of the EC, which thus gets nine member countries.
ISO 8601 weekly numbering is introduced in Norway, Sweden and Denmark.
January 5 - The Netherlands recognizes East Germany.
January 8 - The Watergate scandal: The trial of seven men accused of placing wiretapping equipment at the Democratic Party headquarters begins.
January 15 - Vietnam War: Peace talks move forward, with US President Richard Nixon announcing an end to offensive in North Vietnam.
January 23 - Volcanic eruption on Vestmannaeyjar, Iceland.
February 21 - An Israeli fighter jet shoots down a Libyan passenger plane over the Sinai Desert. 108 people die.
On February 28, 200 Native Americans occupy Wounded Knee in South Dakota, USA in protest of the oppression of the Native American minority.
March 13 - Ageo riots in Japan.
March 21 - Wage negotiations in Denmark break down, 750,000 workers go on strike or are hit by lockouts.
March 29 - Vietnam War: The last US troops leave Vietnam.
April 3 - The world's first mobile phone call is made in New York.
April 4 - The World Trade Center opens in New York.
April 5 - Pierre Messmer becomes Prime Minister of France.
April 6 - The Pioneer 11 spacecraft is launched.
April 10 - Israel attacks targets in Beirut, Lebanon.
April 30 - Watergate scandal: US President Richard Nixon declares responsibility, not guilt.
May 6 - A peace treaty is signed between the Wounded Knee Indians and the authorities.
May 14 - US space station Skylab is launched.
May 19 - Cod War: The British Navy is ordered to protect British fishing vessels fishing within the Icelandic 50-mile border.
May 20 - Cod War: Iceland bans British military aircraft from Keflavik Airport.
June 1 - The military junta in Greece abolishes the kingdom and establishes a republic.
June 3 - The Soviet supersonic plane Tupolev 144 crashes at an air show in Paris, killing 15 people.
June 22 - The Hague Court upholds Australia and New Zealand's demands to ban French nuclear tests in the Pacific. France refuses to recognize the decision.
July 1 - Norway's free trade agreement with the EC enters into force.
July 10 - The Bahamas becomes independent from Britain.
July 11 - Agreement is reached on the Norway-Iceland fisheries agreement.
July 17 - A coup overthrows Afghanistan when Mohammed Daoud Khan seizes power from King Zahir Shah.
July 21 -
New French nuclear tests in the Pacific.
Lillehammer case: In Lillehammer, the Moroccan waiter Ahmed Bouchikhi is murdered by agents from Israeli Mossad.
August 17 - Flood in Pakistan.
23. – 28. August - Norrmalmstorgranet: A bank robber entrenched himself and took hostages in a bank on Norrmalmstorg in Stockholm. This gave name to the Stockholm Syndrome.
September 11 - Military coup in Chile. With the support of the CIA, General Augusto Pinochet's forces overthrow President Salvador Allende and impose a brutal military dictatorship.
September 15 - Carl XVI Gustaf of Sweden becomes King of Sweden.
October 2 - Britain withdraws navy from Icelandic fishing zone following threats of diplomatic breach between the two states.
October 6 - Yom Kippur War: Egypt and Syria attack Israel.
October 20 - Sydney Opera House officially opened by Elizabeth II.
October 24 - Yom Kippur War: Israel-Egypt ceasefire after Israeli forces attack Suez.
November 4 - Oil crisis: OPEC countries adopt oil boycott and price increase as penalty