It was ruled by the monarchs of England and then of Great Britain, and was administered from Dublin Castle by a viceroy appointed by the English king: the Lord Deputy of Ireland.

By the 16th century, the Pale, the area of effective English rule, had shrunk greatly; most of Ireland was held by Gaelic nobles as principalities and chiefdoms.

It authorized the Angevin King Henry II of England to invade Ireland, to bring the country into the European sphere.

When Pope Clement VII excommunicated the king of England, Henry VIII, in 1533, the constitutional position of the lordship in Ireland became uncertain.

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.

The act marked a significant shift in Ireland's political landscape, as it sought to consolidate English control over the island and bring it under closer royal governance.

After the death of Edward VI, Henry's son, the papal bull of 1555 recognised the Roman Catholic Mary I as Queen of Ireland.

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 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.

The Irish Parliament ceased to exist, though the executive, presided over by the Lord Lieutenant, remained in place until 1922.

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.

Contrary to the official plan, the substantial majority of the population remained strongly Roman Catholic, despite the political and economic advantages of membership of the state church.

The legacy of the Kingdom of Ireland remains a bone of contention in Irish-British relations to this day because of the constant ethnic conflict between the native Irish inhabitants and primarily the new Anglo-Irish settlers across the island.

Their background espoused English culture (law, language, dress, religion, economic relations and definitions of land ownership) in Ireland as it later did across much of what was to become the British Empire.

However Gaelic culture and Irish language, was maintained to a significant extent by the majority of the original native population.

Sometimes this was presented as "barbaric", "savage" which later was perceived by the native population as a mark of undesirability in respect of maintaining and learning the language.

There is some perception that during Tudor times, elements within the government at times engaged in and advanced a genocidal[citation needed] policy against the Irish Gaels, while during the Plantations of Ireland (particularly successful in Ulster) the local population were displaced in a project of ethnic cleansing where regions of Ireland became de-Gaelicised.

Some of the native inhabitants, including their leadership, were permitted to flee into exile from the country following ending up on the losing side in conflicts (i.e. the Flight of the Earls and the Flight of the Wild Geese) or in the case of the Cromwellian regime were forced into indentured servitude (although the same happened to English persons involved in the Cromwellian regime) in the Caribbean, following mass land confiscation for the benefit of New English settlers.

On the other hand, the fact that the kingdom had been a unitary state gave Irish nationalists in 1912–22 a reason to expect that in the process of increasing self-government the island of Ireland would be treated as a single political unit.

These earliest arms of Ireland are described in an entry that reads: Le Roi d'Irlande, D'azur à la harpe d'or, in a 13th-century French roll of arms, the Armorial Wijnbergen, also known as the Wijnbergen Roll, said to be preserved in The Hague, in the Netherlands but currently untraced; a copy is held in the Royal Library of Belgium (Collection Goethals, ms. 2569).

This may have been an aspirational depiction for a putative High-King, for it was not related to the Lordship of Ireland at that time by the English king, who only assumed the title "King of Ireland" later in the reign of Henry VIII[13] A crown was not part of the arms but use of a crowned harp was apparently common as a badge or as a device.

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.

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.53°30′N 7°50′W / 53.500°N 7.833°W / 53.500; -7.833