This global war that lasts from 1939 to 1945. The vast majority of the world's countries (including all the great powers) eventually formed two opposing military alliances during the conflict: the Allies and Axis.

A state of total war emerges, directly involving more than 100 million people from over 30 countries. The major participants put their entire economic, industrial, and scientific capabilities behind the war effort, blurring the distinction between civilian and military resources.

This is also the deadliest conflict in human history, marked by 70 to 85 million fatalities, most of whom are civilians in the Soviet Union and China. It includes massacres, the Holocaust genocide, strategic bombing, premeditated death from starvation and disease, and the only use of nuclear weapons in war.

The United Nations (UN) is established after World War II as an intergovernmental organisation tasked with maintaining international peace and security as well as developing friendly relations between nations through international cooperation.

As part of the post-war settlement to prevent further conflicts, the UN succeeds the League of Nations and is established with more powers than its predecessor.

The European Union begins with this, the founding treaty of the Western Union between 1948 and 1954, at which point it is amended as the Modified Treaty of Brussels and serves as the founding treaty of the Western European Union (until its termination in 2010).

The Yom Kippur War is fought by a coalition of Arab states led by Egypt and Syria against Israel, mostly in Sinai and the Golan (occupied by Israel during the 1967 Six-Day War) with some fighting taking place in African Egypt and northern Israel. Egypt's initial war objective is to use its military to seize a foothold on the east bank of the Suez Canal as a means to negotiate the return of the rest of Sinai.

Both the United States and the Soviet Union initiated massive resupply efforts to their respective allies during the war, which leads to a near-confrontation between these two nuclear superpowers. The war has far-reaching effects, including the raising of oil prices by OPEC, which in turn prompted an oil shock in the West one year later.

The 1979 United Kingdom general election sees the Conservative Party led by Margaret Thatcher oust the incumbent Labour government led by James Callaghan.

The Conservative campaign pledges to control inflation and curb the power of the unions, while the Labour campaign is hampered by industrial disputes and strikes during the winter of 1978-79 (known as the Winter of Discontent).

The 1979 election is the first of four consecutive election victories for the Conservative Party, which leads to a radical reshaping of British society as the country shifted to a deregulated, free-market economy.

The 1980 United States presidential election sees Republican Ronald Reagan defeat the incumbent Democrat Jimmy Carter. Due to the rise of conservatism following Reagan's victory, some consider this to be a realigning election that marks the start of the 'Reagan Era'.

During the election campaign, Reagan campaigned for increased defence spending, supply-side economics and a balanced budget. His campaign is aided by Democratic dissatisfaction with Carter, the Iran hostage crisis and deflation (characterised by high unemployment and inflation).

Carter attacks Reagan as a dangerous right-wing extremist, but Reagan goes on to win the election by a landslide, taking a large majority of the electoral vote and 50.7% of the popular vote.

The disintegration within the Union of Soviet Socialist Republics (USSR) begins in the second half of the 1980s with growing unrest in the national republics.

It comes to a head on 26 December 1991, when the USSR is voted out of existence by the Supreme Soviet, following what is known as the Belavezha Accords.

Otherwise known as the Yugoslav Wars, these are a series of ethnic conflicts, wars of independence and insurgencies fought in the former Yugoslavia from 1991 to 2001, which lead to the breakup of the Yugoslav state. Its constituent republics declare independence during the crisis, despite unresolved tensions between ethnic minorities in these emerging countries.

According to the International Center for Transitional Justice, the wars cause the death of 140,000 people, while the Humanitarian Law Center estimates that at least 130,000 people are killed during the conflicts.

The 11 September terrorist attacks on the US are a series of four coordinated attacks by the Islamic terrorist group al-Qaeda that kills 2,977 people, injures over 6,000 others and causes at least $10 billion in infrastructure and property damage.

As part of the attacks, four passenger airliners operated by United Airlines and American Airlines are hijacked by 19 al-Qaeda terrorists. American Airlines Flight 11 and United Airlines Flight 175 are crashed into the North and South towers of the World Trade Center complex in Lower Manhattan.

Within an hour and 42 minutes, both 110-story towers collapsed.

A third plane, American Airlines Flight 77, is crashed into the Pentagon in Virginia and the fourth plane, United Airlines Flight 93, is flown toward Washington, DC, but crashed in Pennsylvania, after its passengers overpower the hijackers.

9/11 is the single deadliest (coordinated) terrorist attack in human history. The United States responds by launching the War on Terror and invading Afghanistan to depose the Taliban, which had failed to comply with the US demands to extradite Osama bin Laden and expel its leader, al-Qaeda, from the country. Al-Qaeda and Osama bin Laden cite US support of Israel, the presence of US troops in Saudi Arabia and sanctions against Iraq as motives for the attacks.

Bin Laden is eventually located in Pakistan and killed by a Navy SEAL team in 2011, and, as a consequence of the attacks, the US has remained in a state of national emergency since 2001.

This constitutes a severe worldwide economic crisis, considered by many economists to be the most serious financial shock since the Great Depression of the 1930s.

It begins in 2007 with a crisis in the subprime mortgage market in the United States and then develops into a full-blown international banking crisis with the collapse of the investment bank Lehman Brothers on 15 September 2008. Excessive risk-taking by banks such as Lehman Brothers helps to magnify the financial impact globally.

Massive bailouts of financial institutions and other monetary and fiscal policies are subsequently employed to prevent a possible collapse of the entire world financial system. The crisis is followed by the global Great Recession.

The 2016 United States presidential election resulted in the Republican businessman Donald Trump defeating Democratic former Secretary of State Hillary Clinton.

Trump wins his party's nomination after defeating Ted Cruz and several other candidates in the 2016 Republican presidential primaries. With Democratic President Barack Obama being term-limited, in the Democratic primaries Clinton defeats her chief rival, Bernie Sanders after a surprisingly hard-fought contest between the two.

Trump goes on to win the general election with 304 of the 538 electoral votes (though Clinton wins the popular vote by a margin of 2.1 percentage points).

Despite the UK government's recommendation that the country remains a member of the EU, in the UK European Union membership referendum of 23 June 2016, 51.9% of voters choose for the United Kingdom to leave the EU.

Three years and seven months later, on 31 January 2020, the UK becomes the first member state to ever leave the European Union.