Flight of the Earls in the context of "Rory O'Donnell, 1st Earl of Tyrconnell"

The Plantation of Ulster (Irish: Plandáil Uladh; Ulster Scots: Plantin o Ulstèr) was the organised colonisation (plantation) of Ulster – a province of Ireland – by people from Great Britain during the reign of King James VI and I.

Small privately funded plantations by wealthy landowners began in 1606, while the official plantation began in 1609. Most of the land had been confiscated from the native Gaelic chiefs, several of whom had fled Ireland for mainland Europe in 1607 following the Nine Years' War against English rule. The official plantation comprised an estimated half a million acres (2,000 km) of arable land in counties Armagh, Cavan, Fermanagh, Tyrone, Donegal, and Londonderry. Land in counties Antrim, Down, and Monaghan was privately colonised with the king's support.

Ireland was conquered by the Tudor monarchs of England in the 16th century. The Anglo-Normans had conquered swathes of Ireland in the late 12th century, bringing it under English rule. In the 14th century, the effective area of English rule shrank markedly, and from then most of Ireland was held by native Gaelic chiefdoms. Following a failed rebellion by the Earl of Kildare in the 1530s, the English Crown set about restoring its authority. Henry VIII of England was made "King of Ireland" by the Crown of Ireland Act 1542. The conquest involved assimilating the Gaelic nobility by way of "surrender and regrant"; the confiscation and colonisation ('plantation') of lands with settlers from Britain; imposing English law and language; banning Catholicism, dissolving the monasteries, and making Anglican Protestantism the state religion.

The Tudor policies in Ireland sparked the Desmond Rebellions (1569–1573, 1579–1583) and the Nine Years' War (1594–1603). Despite Spain sending an armada to support the Irish Catholics during the Anglo-Spanish War (1585–1604), by 1603 the entire country was under English rule. The Flight of the Earls in 1607 largely completed the destruction of the Gaelic aristocracy and left the way open for the Plantation of Ulster, which established a large British Protestant population in the north. Several people who helped establish the plantations of Ireland also played a part later in the early colonisation of North America, particularly a group known as the West Country Men.

The Protestant Ascendancy (Irish: An Chinsealacht Phrotastúnach; also known as the Ascendancy) was the sociopolitical and economical domination of Ireland between the 17th and early 20th centuries by a small Anglican ruling class, whose members consisted of landowners, barristers, politicians, clergymen, military officers and other prominent professions. They were either members of the Church of Ireland or the Church of England and wielded a disproportionate amount of social, cultural and political influence in Ireland. The Ascendancy existed as a result of British rule in Ireland, as land confiscated from the Irish Catholic aristocracy was awarded by the Crown to Protestant settlers from Great Britain.

During the Tudor conquest of Ireland, land owned by Irish nobles was gradually confiscated by the Crown over several decades. These lands were sold to colonists from Great Britain as part of the plantations of Ireland, with the province of Ulster being a focus in particular for colonisation by Protestant settlers after the Battle of Kinsale. These settlers went on to form the new aristocracy and gentry of Ireland, as the Gaelic nobility had either died, fled with the Flight of the Earls or allied with the Crown. They eventually came to be known as the Anglo-Irish people. From the 1790s the phrase became used by the main two identities in Ireland: nationalists, who were mostly Catholics, used the phrase as a "focus of resentment", while for unionists, who were mostly Protestants, it gave a "compensating image of lost greatness".

For centuries, Spain recruited foreign soldiers to its army, forming the foreign regiments (Infantería de línea extranjera) such as the Regiment of Hibernia (formed in 1709 from Irishmen who fled their own country in the wake of the Flight of the Earls and the penal laws). However, the specific unit of the Spanish Army and Spain's Rapid Reaction Force, now known as the Spanish Legion (Legión Española, La Legión), and informally known as the Tercio or the Tercios, is a 20th-century creation. It was raised in the 1920s to serve as part of Spain's Army of Africa. The unit, which was established in January 1920 as the Spanish equivalent of the French Foreign Legion, was initially known as the Tercio de Extranjeros ("Tercio of foreigners"), the name under which it began fighting in the Rif War of 1921–1926.

Over the years, the force's name has changed from Tercio de Extranjeros to Tercio de Marruecos (when the field of operations targeted Morocco), and by the end of the Rif War it became the "Spanish Legion", with several "tercios" as sub-units.

The O'Neill dynasty (Irish: Ó Néill) are a lineage of Irish Gaelic origin that held prominent positions and titles in Ireland and elsewhere. As kings of Cenél nEógain, they were historically one of the most prominent family of the Northern Uí Néill, along with the O'Donnell dynasty. Some O'Neills state that their ancestors were kings of Ailech during the Early Middle Ages, as descendants of Niall of the Nine Hostages.

Two of their progenitors were High Kings of Ireland: Niall Glúndub (from whom they take their name) and Domnall ua Néill. From 1232 until 1616, the O'Neills were sovereign kings of Tír Eógain, holding territories in the north of Ireland in the province of Ulster, particularly around modern County Tyrone, County Londonderry and County Antrim, in what is now Northern Ireland. After their territory was merged with the Kingdom of Ireland and the land was caught up in the Plantation of Ulster, they were involved in a number of events, such as Tyrone's Rebellion, the Flight of the Earls, the Irish Rebellion of 1641 and the Irish Confederate Wars.

Tyrconnell (Irish: Tír Chonaill, meaning 'Land of Conall'), also spelled Tirconnell and Tirconaill, was a kingdom of Gaelic Ireland. It is associated geographically with present-day County Donegal, which was officially named County Tirconaill between 1922 and 1927. At times it also included parts of County Fermanagh, County Sligo, County Leitrim, County Tyrone and County Londonderry at its greatest extent. The kingdom represented the core homeland of the Cenél Conaill people of the Northern Uí Néill and although they ruled, there were smaller groups of other Gaels in the area.

From the 5th century founding of Cenél Conaill, the tuatha was a sub-unit of the larger kingdom of Ailech, along with their Cenél nEógain cousins, fellow descendants of Niall of the Nine Hostages. Their initial ascent had coincided with the decline of the Ulaid, whose kingdom of Ulster receded to the north-east coast. In the 12th century the kingdom of Ailech split into two sovereign territories and Cenél Conaill became Tír Chonaill under the Ó Domhnaill (O'Donnell) clan. It was the location of fighting during the Nine Years' War (Ireland) at the end of the 16th century. It continued to exist until the 17th century when it was incorporated into the English-ruled Kingdom of Ireland following the Flight of the Earls.