| 4 January - 31 January 2004 | [space exploration] | Two US space probes, Spirit and Opportunity, land successfully on Mars to begin investigations into whether the planet ever had water and if it could have supported life. By the end of the month there remains no contact with the British Beagle 2 probe which should have touched down on Mars on 25 December 2003. |
| 14 January 2004 | USA [business and economics] | New York-based bank J P Morgan Chase announces a takeover worth nearly US$60 billion of Chicago-based rival Bank One. The combined company will become the second-largest banking operation in the USA after Citigroup. |
| February 2004 | Iraq [Second Gulf War (2003)] | Iraq suffers a wave of suicide bombings and insurgent attacks in Irbil, Iskandariya, Baghdad, Falluja and Kirkuk, killing about 230 people during February. Meanwhile, the US and UK governments each set up an inquiry into intelligence failures about Saddam Hussein's alleged weapons of mass destruction. The UK government's case for war is further undermined as it abandons the prosecution of an employee who leaked information about US and UK plans to bug United Nations Security Council delegations in the run-up to the war – further claims about which are aired publicly by former cabinet minister Clare Short. |
| 2 February 2004 | Israel, Palestine [diplomacy] | In the Middle East, Israeli prime minister Ariel Sharon announces that he will remove all Jewish settlements in Gaza as part of his plan to disengage unilaterally from territories occupied since 1967, leaving a rump self-governing Palestinian state behind Israel's controversial West Bank security wall. |
| 29 March 2004 | Ireland [public health] | The Republic of Ireland becomes the first country in the world to introduce a nationwide ban on smoking in every workplace. |
| 29 March 2004 | [international organizations] | The North Atlantic Treaty Organization (NATO) welcomes seven new members, as Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia, and Slovenia formally join the western political and military alliance. Their accession brings the total membership of NATO to 26 countries. |
| 24 April 2004 | Cyprus [political events] | A referendum is held in the ethnically divided island of Cyprus on a United Nations (UN) plan for political reunification based on a proposed federation of two largely autonomous states. Although the Turkish Cypriot community endorses the plan, about 75% of the majority Greek Cypriot population rejects it, confirming fears that Cyprus will join the European Union (EU) on 1 May 2004 as a partitioned nation. |
| 1 May 2004 | [international organizations] | The European Union (EU) expands to cover 450 million citizens as eight central European states – the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Slovakia, and Slovenia – together with Cyprus and Malta, become full members of the organization. The enlargement from 15 to 25 countries is the biggest in EU history. |
| 19 May 2004 | England [physiology] | The world's first stem-cell bank opens in Hertfordshire, England, based at the National Institute for Biological Standards and Control. Stem cell research, although controversial, has the potential to accelerate the development of regenerative medicine. |
| 5 June 2004 | USA [births and deaths] | Ronald Reagan, former actor turned Republican politician and 40th President of the USA 1981–89, dies in California (93). |
| 10 June 2004 | USA [births and deaths] | Ray Charles, legendary US soul, blues, and jazz singer, dies in Beverly Hills, California (73). |
| 21 June 2004 | [space exploration] | SpaceShipOne (SS-1) becomes the world's first crewed commercial craft in space. Taking off from the Mojave desert in California, the privately-built SS-1 piloted by Mike Melvill breaks out of Earth's atmosphere to briefly touch the edge of space at an altitude of 100 km/62 mi. |
| 1 July 2004 | USA [births and deaths] | Marlon Brando, iconic US Academy Award-winning cinema actor who starred in films such as On the Waterfront (1954), The Godfather (1972), and Apocalypse Now (1979), dies in Los Angeles, California (80). |
| 4 July 2004 | Portugal [football] | Greece is the unexpected winner of football's 2004 European Championship, beating the host country Portugal 1–0 in the final in Lisbon. |
| 9 July - 14 July 2004 | UK, USA [Second Gulf War (2003)] | A committee of inquiry chaired by Lord Butler delivers its report on the UK government's justification for going to war against Saddam Hussein's regime in Iraq in 2003. It criticises the seriously flawed quality of intelligence about Iraqi weapon capabilities, but finds that there was no deliberate attempt on the part of the government to mislead and apportions no blame to individuals. The Butler report follows a few days after a more damning assessment of US intelligence failures on Iraq by the US Senate Intelligence Committee. |
| 21 July 2004 | UK [physiology] | In a significant change of policy towards ‘designer babies’, the UK Human Fertilisation and Embryology Authority approves tissue-matching tests on embryos for the purposes of saving the life of a sick older brother or sister. |
| 13 August 2004 | Greece [Olympic Games] | The 28th Olympic Games open in Athens, Greece, attended by more than 10,500 competitors representing 202 national teams in 301 medal events. |
| 18 August - 19 August 2004 | [business and economics] | Google, the world's largest Internet web search engine, makes its stock market debut after its initial public offering (IPO) is approved by the US Securities and Exchange Commission. However, it cuts the price range for its IPO and the number of shares for sale, valuing the company at about US$23 billion rather than the US$35 billion previously anticipated. |
