Acts of Union 1800
Long titleAn Act for the Union of Great Britain and Ireland
Citation40 Geo. 3 c.38
Introduced byJohn Toler[1]
Royal assent1 August 1800
Commencement1 January 1801
Status: Amended
Revised text of statute as amended

The Acts of Union 1800 (sometimes incorrectly referred to as a single 'Act of Union 1801') were parallel acts of the Parliament of Great Britain and the Parliament of Ireland which united the Kingdom of Great Britain and the Kingdom of Ireland (previously in personal union) to create the United Kingdom of Great Britain and Ireland. The acts came into force on 1 January 1801, and the merged Parliament of the United Kingdom had its first meeting on 22 January 1801.

Both acts remain in force, with amendments and some Articles repealed, in the United Kingdom of Great Britain and Northern Ireland,[2] but have been repealed in its entirety in the Republic of Ireland.[3]


Two acts were passed in 1800 with the same long title, An Act for the Union of Great Britain and Ireland. The short title of the act of the British Parliament is Union with Ireland Act 1800, assigned by the Short Titles Act 1896. The short title of the act of the Irish Parliament is Act of Union (Ireland) 1800, assigned by a 1951 act of the Parliament of Northern Ireland, and hence not effective in the Republic of Ireland, where it was referred to by its long title when repealed in 1962.


Before these Acts, Ireland had been in personal union with England since 1541, when the Irish Parliament had passed the Crown of Ireland Act 1542, proclaiming King Henry VIII of England to be King of Ireland. Since the 12th century, the King of England had been technical overlord of the Lordship of Ireland, a papal possession. Both the Kingdoms of Ireland and England later came into personal union with that of Scotland upon the Union of the Crowns in 1603.

In 1707, the Kingdom of England and the Kingdom of Scotland were united into a single kingdom: the Kingdom of Great Britain. Upon that union, each House of the Parliament of Ireland passed a congratulatory address to Queen Anne, praying that, "May God put it in your royal heart to add greater strength and lustre to your crown, by a still more comprehensive Union".[4] The Irish Parliament was both before then subject to a certain restrictions that made it subordinate to the Parliament of England and after then, to the Parliament of Great Britain; however, Ireland gained effective legislative independence from Great Britain through the Constitution of 1782.

By this time access to institutional power in Ireland was restricted to a small minority: the Anglo-Irish of the Protestant Ascendancy. Frustration at the lack of reform among the Catholic majority eventually led, along with other reasons, to a rebellion in 1798, involving a French invasion of Ireland and the seeking of complete independence from Great Britain. This rebellion was crushed with much bloodshed, and the motion for union was motivated at least in part by the belief that the rebellion was exacerbated as much by brutally reactionary loyalists as by United Irishmen (anti-unionists).[citation needed]

Furthermore, Catholic emancipation was being discussed in Great Britain, and fears that a newly enfranchised Catholic majority would drastically change the character of the Irish government and parliament also contributed to a desire from London to merge the Parliaments.[citation needed]

Name Flag Population
Pop. density
(per km²)
Kingdom of Great Britain
10,500,000 65% 230,977 73% 45.46
Kingdom of Ireland
5,500,000 35% 84,421 27% 65.15
United Kingdom
16,000,000 100% 315,093 100% 50.78


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Complementary acts had to be passed in the Parliament of Great Britain and in the Parliament of Ireland.

The Parliament of Ireland had recently gained a large measure of legislative independence under the Constitution of 1782. Many members of the Irish Parliament jealously guarded that autonomy (notably Henry Grattan), and a motion for union was legally rejected in 1799. Only Anglicans were permitted to become members of the Parliament of Ireland though the great majority of the Irish population were Roman Catholic, with many Presbyterians in Ulster. In 1793 Roman Catholics regained the right to vote if they owned or rented property worth £2 annually. Wealthy Catholics were strongly in favour of union in the hope for rapid religious emancipation and the right to sit as MPs, which came to pass only well after the religiously divisive Napoleonic Wars, namely under the Roman Catholic Relief Act 1829.

From the perspective of Great Britain's elites, the union was desirable because of the uncertainty that followed the Irish Rebellion of 1798 and the French Revolution of 1789; if Ireland adopted Catholic emancipation willingly or not, a Roman Catholic Parliament could break away from Britain and ally with the French, but the same measure within the United Kingdom would exclude that possibility. Also the Irish and British Parliaments in creating a regency during King George III's "madness", gave the Prince Regent different powers. These considerations led Great Britain to decide to attempt the merger of both kingdoms and Parliaments.

The final passage of the Act in the Irish Commons turned on an about 16% relative majority, garnering 58% of the votes, and similar in the Irish Lords, in part per contemporary accounts through bribery with the awarding of peerages and honours to critics to get votes.[5] The first attempt had been defeated in the Irish House of Commons by 109 votes to 104, but the second vote in 1800 passed by 158 to 115.[5]


The Acts of Union were two complementary Acts, namely:

They were passed on 2 July 1800 and 1 August 1800 respectively, and came into force on 1 January 1801. They ratified eight articles which had been previously agreed by the British and Irish parliaments:

Part of the attraction of the Union for many Irish Catholics was the promise of Catholic Emancipation, allowing Roman Catholic MPs, who had not been allowed in the Irish Parliament. This was however blocked by King George III who argued that emancipating Roman Catholics would breach his Coronation Oath, and was not realised until 1829.

The traditionally separate Irish Army, which had been funded by the Irish Parliament, was merged into the larger British Army.

The first parliament

In the first Parliament of the United Kingdom of Great Britain and Ireland, the members of the House of Commons were not elected afresh. By royal proclamation authorised by the Act, all the members of the last House of Commons from Great Britain took seats in the new House, and from Ireland 100 members were chosen from the last Irish House of Commons: two members from each of the 32 counties and from the two largest boroughs, and one from each of the next 31 boroughs (chosen by lot) and from Dublin University. The other 84 Irish parliamentary boroughs were disfranchised; all were pocket boroughs, whose patrons received £15,000 compensation for the loss of what was considered their property.


Change in the Union Flag
Earlier Flag of Great Britain,
prior to the union with Ireland
The second Union Flag,
incorporating the Irish Saint Patrick's Saltire

Main article: Union Jack

The Union Flag, created as a consequence of the union of the Kingdom of Great Britain and Ireland in 1800, still remains the flag of the United Kingdom. Called the Union Flag, it combined the flags of St George's Cross (which was deemed to include Wales) and the St Andrew's Saltire of Scotland with the St Patrick's Saltire to represent Ireland (it now represents Northern Ireland). At the same time, the moribund English claims to the French throne were given up, so the fleur-de-lis were removed from the Royal Standard of the United Kingdom.


  1. ^ "Bill 4098: For the union of Great Britain and Ireland". Irish Legislation Database. Belfast: Queen's University. Archived from the original on 25 February 2015. Retrieved 28 April 2015.
  2. ^ From
  3. ^ From Irish Statute Book:
  4. ^ Journals of the Irish Commons, vol. iii. p. 421
  5. ^ a b Alan J. Ward, The Irish Constitutional Tradition p.28.
  6. ^ "Union with Ireland Act 1800".  No. (39 & 40 Geo. 3 c. 67) of 2 July 1800. Retrieved 6 September 2015. Archived 6 July 2019 at the Wayback Machine
  7. ^ "Act of Union (Ireland) 1800".  No. (40 Geo. 3 c. 38) of 1 August 1800. Retrieved 6 September 2015. Archived 17 June 2019 at the Wayback Machine
  8. ^ "Brexit: NI Protocol is lawful, High Court rules". BBC News. 30 June 2021. Archived from the original on 30 June 2021. Retrieved 2 July 2021.
  9. ^ Erwin, Alan (29 November 2021). "NI Protocol conflicts with Acts of Union, court told during legal challenge from unionists". Belfast Telegraph.



Further reading


  1. ^ The Northern Ireland High Court ruling is currently under appeal [9]