The United Kingdom of Great Britain and Northern Ireland is a sovereign state. England, Scotland, Wales (together: Great Britain) and Northern Ireland are parts of this state.

The Acts of Union in 1707 united the crowns and Parliaments of England and Scotland to create (the United Kingdom of) Great Britain. At this time, Wales was legally part of the Kingdom of England, with representation (since 1536) in the English Parliament, so it was included in the union of England and Scotland. Ireland was a separate kingdom with its own parliament until further Acts of Union in 1800 joined Great Britain and Ireland to create the United Kingdom of Great Britain and Ireland.

In 1922, the territory of what is now the Republic of Ireland gained independence, and only Northern Ireland continued to be part of the United Kingdom. As a result, in 1927 Britain changed its formal title to "The United Kingdom of Great Britain and Northern Ireland", usually shortened to "the United Kingdom", "The UK", "Great Britain" or just "Britain".

The birth of the United Kingdom

Acts of Union 1707

The first step towards political unification were taken on 1 May 1707, when the parliaments of Scotland and England approved Acts of Union which combined the two parliaments and the two royal titles.

Perhaps the greatest single benefit to Scotland of the Union was that Scotland could enjoy free trade with England and her colonies overseas. For England's part, a possible ally for European states that were hostile to England had been neutralized.

Certain aspect of the former independent kingdoms remained separate. Examples of Scottish and English institutions which were not merged into the British system include: Scottish and English law which remain separate, as do Scottish and English banking systems, the Presbyterian Church of Scotland and Anglican Church of England also remained separate as did the systems of education and higher learning.

As the Scots were generally well educated, they made a disproportionate contribution to both the government of the United Kingdom and the administration of the British Empire.

19th century

Ireland joins with the Act of Union (1800)

The second stage in the development of the United Kingdom took effect on 1 January 1801, when Great Britain merged with the Ireland to form the United Kingdom of Great Britain and Ireland.

The legislative union of Great Britain and Ireland was completed under the Act of Union 1800. The country's name was changed to "United Kingdom of Great Britain and Ireland". The Act was passed in the British and therefore unrepresentative Irish Parliament with substantial majorities achieved in part (according to contemporary documents) through bribery, namely the awarding of peerages and honors to critics to get their votes. The separate Parliaments of Great Britain and Ireland were abolished, and replaced by a united Parliament of the United Kingdom. Ireland thus became part of an extended United Kingdom. Ireland sent around 100 MPs to the House of Commons at Westminster and 28 peers to the House of Lords.

Napoleonic wars
Hostilities between Great Britain and France recommenced on 18 May 1803. The Coalition war-aims changed over the course of the conflict: a general desire to restore the French monarchy became closely linked to the struggle to stop Napoleon.
The Napoleonic conflict had reached the point at which subsequent historians could talk of a "world war". Only the Seven Years' War offered a precedent for widespread conflict on such a scale.

Victorian era 
The Victorian era marked the height of the British Industrial Revolution and the apex of the British Empire. Although commonly used to refer to the period of Queen Victoria's rule between 1837 and 1901, scholars debate whether the Victorian period–as defined by a variety of sensibilities and political concerns that have come to be associated with the Victorians–actually begins with the passage of Reform Act 1832. The era was preceded by the Regency era and succeeded by the Edwardian period. The latter half of the Victorian era roughly coincided with the first portion of the Belle Époque era of continental Europe and other non-English speaking countries.

Prime Ministers: William Pitt the Younger | Lord Grenville | Duke of Portland | Spencer Perceval | Lord Liverpool | George Canning | Lord Goderich | Duke of Wellington | Lord Grey | Lord Melbourne | Sir Robert Peel | Lord John Russell | Lord Derby | Lord Aberdeen | Lord Palmerston | Benjamin Disraeli | William Ewart Gladstone | Lord Salisbury | Lord Rosebery

Ireland and the move to Home Rule

20th century

Prime Ministers of the United Kingdom 1900–1945
Marquess of Salisbury | Arthur Balfour | Sir Henry Campbell-Bannerman | Herbert Henry Asquith | David Lloyd George | Andrew Bonar Law | Stanley Baldwin | Ramsay MacDonald | Stanley Baldwin | Ramsay MacDonald | Stanley Baldwin | Neville Chamberlain | Winston Churchill

World War I

Partition of Ireland

World War II

Empire to Commonwealth 
Britain's control over its Empire loosened during the interwar period. Nationalism became stronger in other parts of the empire, particularly in India and in Egypt.

Between 1867 and 1910, the UK granted Australia, Canada, and New Zealand "Dominion" status (near complete autonomy within the Empire).

1945-1997
The end of the Second World War saw a landslide General Election victory for Clement Attlee and the Labour Party.

As the country headed into the 1950s, rebuilding continued and a number of immigrants from the remaining British Empire were invited to help the rebuilding effort. During the 1950s the UK lost its place as a superpower and could no longer maintain its large Empire. This led to decolonization, and a withdrawal from almost all of its colonies by 1970.

Though the 1970s and 1980s saw the UK's integration to the European Economic Community which became the European Union in 1992 and a strict modernization of its economy.

After the difficult 70s and 80s the 1990s saw the beginning of a period of continuous economic growth that has to date lasted over 15 years. The Good Friday Agreement saw what many believe to be the beginning of the end of conflict in Northern Ireland; since this event, there has been very little armed violence over the issue.

21st century 
In the 2001 General Election, the Labour Party won a second successive victory.

Despite huge anti-war marches being held in London and Glasgow, Tony Blair gave strong support to the United State's invasion of Iraq in 2003. Forty-six thousand British troops, one-third of the total strength of the British Army (land forces), were active to assist with the invasion of Iraq and after that British armed forces were responsible for security in southern Iraq in the time before the Iraqi elections of January 2005.

2007 saw the conclusion of the premiership of Tony Blair, followed by that of Gordon Brown. The next prime minister, David Cameron, was elected in 2010. During his first term, the Scottish National Party (SNP) won the 2011 election to the Scottish Parliament. On 18 September 2014, the SNP held a referendum that asked the people of Scotland whether they want to be independent from the UK. 55% of voters wanted to remain in the UK.

David Cameron was re-elected in 2015 on promises to hold a referendum on whether the United Kingdom should leave the European Union. It took place on 23 June 2016 and was won by the "Leave" campaign with 52% of the vote. Cameron would then resign and be replaced by Theresa May as prime minister who will lead the country into the process of "Brexit".

On January 2020, Brexit had occurred.

Terrorist attacks 
The U.K. also saw two incidents of terrorism occur in London in the 21st century.

On 7 July 2005, three bombs exploded on the London Underground at 8:50 during the morning rush hour, and a fourth exploded one hour later on a bus in Tavistock Square. The attack, done by Muslim extremists, killed 52 people and injured over 700 others.

On 22 March 2017, exactly one year after the bombings in Brussels, five people were killed in the 2017 Westminster attack near the Houses of Parliament. One of them was the attacker, Khalid Masood, who also stabbed an officer of the Metropolitan Police, who later died of his injuries.

On 22 May 2017, "two bombings" occurred at the Manchester Arena with 19 people dead and 50 injured. It is a suspected suicide bombing.

Related pages
 United Kingdom
 British Empire
 History of Europe
 History of England

Footnotes 
¹ The term "United Kingdom" was first used in the Union with Scotland Act 1706. However it is generally seen as a descriptive term, indicating that the kingdoms were freely united rather than through conquest. It is not seen as being actual name of the new United Kingdom, which was (by article one) "Great Britain". The "United Kingdom" as a name is taken to refer to the kingdom that emerged when the Kingdom of Great Britain and Kingdom of Ireland merged on 1 January 1801.

² The name "Great Britain" (then spelt "Great Brittaine") was first used by James VI/I in October 1604, who indicated that henceforth he and his successors would be viewed as Kings of Great Britain, not Kings of England and Scotland. However the name was not applied to the state as a unit; both England and Scotland continued to be governed independently. Its validity as a name of the Crown is also questioned, given that monarchs continued using separate ordinals (e.g., James VI/I, James VII/II) in England and Scotland. To avoid confusion, historians generally avoid using the term "King of Great Britain" until 1707 and instead to match the ordinal usage call the monarchs kings or queens of England and Scotland. Separate ordinals were abandoned when the two states merged with the Act of Union 1707, with subsequent monarchs using ordinals apparently based on English not Scottish history (it might be argued that the monarchs have simply taken the higher ordinal, which to date has always been English). One example is Queen Elizabeth II of the United Kingdom, who is referred to as being "the Second" even though there never was an Elizabeth I of Scotland or Great Britain. Thus the term "Great Britain" is generally used from 1707.

³ The number changed several times between 1801 and 1922.

4 The Anglo-Irish Treaty was ratified by (i) The British Parliament (Commons, Lords & Royal Assent), (ii) Dáil Éireann, and the (iii) the House of Commons of Southern Ireland, a parliament created under the British Government of Ireland Act 1920 which was supposedly the valid parliament of Southern Ireland in British eyes and which had an almost identical membership of the Dáil, but which nevertheless had to assemble separately under the Treaty's provisions to approve the Treaty, the Treaty thus being ratified under both British and Irish constitutional theory.

References

Other websites 
 Info Britain.co.uk 
 History of the United Kingdom: Primary Documents
 http://www.british-history.ac.uk
 Text of 1800 Act of Union 
 Act of Union virtual library