Kingdom of Ireland The Kingdom of Ireland ( , Modern spelling : " Ríocht Éireann " ) refers to the country of Ireland in the period between the proclamation of Henry VIII as King of Ireland by the Crown of Ireland Act 1542 and the Act of Union in 1800 . It replaced the Lordship of Ireland , which had been created in 1171 . King Henry VIII was recognised as monarch of Ireland by some Protestant powers in Europe , although not by the Catholic monarchies in Europe . However , his daughter Mary I was recognised as Queen of Ireland by the pope in 1555 . The separate Kingdom of Ireland ceased to exist at the end of 1800 , as Ireland joined with Great Britain to form the United Kingdom of Great Britain and Ireland on the first day of 1801 . Background and early history . The papal bull " Laudabiliter " of Pope Adrian IV was issued in 1155 . It granted the Angevin King Henry II of England the title " Dominus Hibernae " ( Latin for " Lord of Ireland " ) . " Laudabiliter " authorised the king to invade Ireland , to bring the country into the European sphere . In return , Henry was required to remit a penny per hearth of the tax roll to the Pope . This was reconfirmed by Adrian ' s successor Pope Alexander III in 1172 . When Pope Clement VII excommunicated the king of England , Henry VIII , in 1533 , the constitutional position of the lordship in Ireland became uncertain . Henry had broken away from the Holy See and declared himself the head of the Church in England . He had petitioned Rome to procure an annulment of his marriage to Queen Catherine . Clement VII refused Henry ' s request and Henry subsequently refused to recognise the Roman Catholic Church ' s vestigial sovereignty over Ireland , and was excommunicated again in late 1538 by Pope Paul III . The Treason Act ( Ireland ) 1537 was passed to counteract this . Following the failed revolt of Silken Thomas in 1534 – 35 , Grey , the lord deputy , had some military successes against several clans in the late 1530s , and took their submissions . By 1540 most of Ireland seemed at peace and under the control of the king ' s Dublin administration ; a situation that was not to last for long . Henry was proclaimed King of Ireland by the Crown of Ireland Act 1542 , an Act of the Irish Parliament . The new kingdom was not recognised by the Catholic monarchies in Europe . After the death of King Edward VI , Henry ' s son , the papal bull of 1555 recognised the Roman Catholic Queen Mary I as Queen of Ireland . The link of " personal union " of the Crown of Ireland to the Crown of England became enshrined in Catholic canon law . In this fashion , the Kingdom of Ireland was ruled by the reigning King of England . This placed the new Kingdom of Ireland in personal union with the Kingdom of England . In line with its expanded role and self - image , the administration established the King ' s Inns for barristers in 1541 , and the Ulster King of Arms to regulate heraldry in 1552 . Proposals to establish a university in Dublin were delayed until 1592 . In 1603 James VI King of Scots became James I of England , uniting the Kingdoms of England , Scotland and Ireland in a personal union . The political order of the kingdom was interrupted by the Wars of the Three Kingdoms starting in 1639 . During the subsequent interregnum period , England , Scotland and Ireland were ruled as a republic until 1660 . This period saw the rise of the loyalist Irish Catholic Confederation within the kingdom and , from 1653 , the creation of the republican Commonwealth of England , Scotland and Ireland . The kingdom ' s order was restored 1660 with the restoration of Charles II . Without any public dissent , Charles ' s reign was backdated to his father ' s execution in 1649 . Political union between England and Scotland was established in 1707 with the creation of the Kingdom of Great Britain . Viceroy . The Kingdom of Ireland was governed by an executive under the control of a " Lord Deputy " or viceroy . The post was held by senior nobles such as Thomas Radcliffe . From 1688 the title was usually " Lord Lieutenant " . In the absence of a Lord Deputy , lords justices ruled . While some Irishmen held the post , most of the lords deputy were English noblemen . While the viceroy controlled the Irish administration as the monarch ' s representative , in the eighteenth century the political post of Chief Secretary for Ireland became increasingly powerful . The Kingdom of Ireland was legislated by the bicameral Parliament of Ireland , made up of the House of Lords and the House of Commons . The powers of the Irish parliament were circumscribed by a series of restrictive laws , mainly Poynings ' Law of 1494 . Church of Ireland . When the church in England broke communion from the Roman Catholic Church , all but two of the bishops of the Church in Ireland followed the Church of England , although almost no clergy or laity did so . The new body became the State Church , assuming possession of most Church property ( and so retaining a great repository of religious architecture and other items , though some were later destroyed ) . The substantial majority of the population remained strongly Roman Catholic , despite the political and economic advantages of membership in the state church . Despite its numerical minority , however , the Church of Ireland remained the official state church until it was disestablished on 1 January 1871 by the Liberal government under William Ewart Gladstone . Parliament of the Kingdom of Ireland . Roman Catholics and dissenters , mostly Presbyterians , Baptists , and Methodists , were excluded from membership of the Irish parliament from 1693 and their rights were restricted by a series of laws called the Penal Laws . They were denied voting rights from 1728 until 1793 . The Grattan Parliament succeeded in achieving the repeal of Poynings ' Law in 1782 . This allowed progressive legislation and gradual liberalisation was effected . Catholics and Dissenters were given the right to vote in 1793 , but Catholics were still excluded from the Irish Parliament and senior public offices in the kingdom . As in Great Britain and the rest of Europe , voting and membership of parliament was restricted to property owners . In the 1720s the new Irish Houses of Parliament was built in College Green , Dublin . Grattan ' s Parliament . Poynings ' Law was repealed in 1782 in what came to be known as the Constitution of 1782 , granting Ireland legislative independence . Parliament in this period came to be known as Grattan ' s Parliament , after the principal Irish leader of the period , Henry Grattan . Although Ireland had legislative independence , executive administration remained under the control of the executive of the Kingdom of Great Britain . In 1788 – 89 a Regency crisis arose caused when King George III became ill . Grattan wanted to appoint the Prince of Wales , later George IV , as Regent of Ireland . The king recovered before this could be enacted . Union with Great Britain . The Irish Rebellion of 1798 , and the rebels ' alliance with Great Britain ' s longtime enemy the French , led to a push to bring Ireland formally into the British Union . By the Act of Union , voted for by the Irish Parliament , the Kingdom of Ireland merged in 1801 with the Kingdom of Great Britain to form the United Kingdom of Great Britain and Ireland . The Irish Parliament ceased to exist , though the executive , presided over by the Lord Lieutenant , remained in place until 1922 . The union was later the subject of much controversy . In 1937 , the link to the UK Crown was repealed , but the monarch was the " de jure " King in the new State until 1949 . In the Republic of Ireland the 1542 Act was repealed in 1962 . Notes . The arms of the Kingdom of Ireland were blazoned : " azure , a harp or string argent " . A crown was not part of the arms but use of a crowned harp was apparently common as a badge or as a device . A crowned harp also appeared as a crest although the delineated crest was : " a wreath or and azure , a tower ( sometime triple - towered ) or , from the port , a hart springing argent " . " King James not only used the harp crowned as the device of Ireland , but quartered the harp in this royal achievement for the arms of that kingdom , in the third quarter of the royal achievement upon his Great Seal , as it has continued ever since . The blazon was azure , a harp or string argent , as appears by the great embroidered banner , and at the funeral of Queen Anne , King James ' queen , AD 1618 , and likewise by the great banner and banner of Ireland at the funeral of King James . The difference between the arms and device of Ireland appears to be on the crown only , which is added to the harp when used as a device . " At the funeral of King James was likewise carried the standard of the crest of Ireland , a buck proper ( argent in the draught ) issuing from a tower triple towered or , which is the only instance of this crest that I have met , and therefore was probably devised and assigned for the crest of Ireland upon occasion of this funeral , but with what propriety I do not understand . " – Questions and Answers , Notes and Queries , 1855 , p . 350 " The insignia of Ireland have variously been given by early writers . In the reign of Edward IV , a commission appointed to enquire what were the arms of Ireland found them to be three crowns in pale . It has been supposed that these crowns were abandoned at the Reformation , from an idea that they might denote the feudal sovereignty of the pope , whose vassal the king of England was , as lord of Ireland . However , in a manuscript in the Heralds ' College of the time of Henry VII , the arms of Ireland are blazoned azure , a harp or , stringed argent ; and when they were for the first time placed on the royal shield on the accession of James I . they were thus delineated : the crest is on a wreath or and azure , a tower ( sometime triple - towered ) or , from the port , a hart springing argent . Another crest is a harp or . The national flag of Ireland exhibits the harp in a field vert . The royal badge of Ireland , as settled by sign - manual in 1801 is a harp , or , stringed argent , and a trefoil vert , both ensigned with the imperial crown . " – Chambers ' s Encyclopædia : A Dictionary of Universal Knowledge , 1868 , p . 627