Migratory flows (16th–19th century)

At that time, there were two catholic communities living in Ireland : The Irish, that is the Gaelic^[1] speaking populations and the Old English of Anglo-Norman descent entrenched in the island since the 12^th century. These Old English were hard to tell apart from the Irish as they dressed like them, much to the dismay of the Protestant new-comers freshly arrived from Great Britain.

England had become Anglican during Elizabeth I's reign. Anglicanism is a compromise between Protestantism and Catholicism. Liturgically^[2] it remains close to the Catholic church the episcopal hierarchy of which it has also retained. Several innovations, however, are distinctly Protestant. In 1559 the reestablishment of the Act of Supremacy^[3] (temporarily abolished by Catholic Mary I) made the English sovereign « the supreme governor of the Church in England [to whom] appertains the government of all estates whether civil or ecclesiastical, in all causes » ; The Church of England was thence separated from Rome. Furthermore the doctrinal position stated in the Thirty-nine Articles^[4] connotes a Calvinist dogma. This text adopted in 1563 by the clergy and in 1571 by Parliament does indeed reject such articles of faith as Purgatory^[5], indulgences^[6] and the worship of relics^[7], it upholds « salvation by faith » and not « by works », acknowledges the dogma of predestination^[8] and admits only of two sacraments^[9] : baptism and « the supper of the Lord » (Holy Communion). The Book of Common Prayer adopted in 1599 was inspired by Calvinist teaching.

From the end of the 16^th century, the English set out to disseminate Protestant Reformation in Ireland. With this in mind Elisabeth's administration was the main agent of a cautious Anglicisation of the island. It encouraged the settlement of Anglican communities ; in other words, it colonised in order to reinforce its own authority and to help affirm Protestantism in two of its main currents : Anglicanism and Presbyterianism.

Indeed, besides the English, the Scots also arrived in numbers to settle the island. Under the influence of John Knox^[10] and the Edinburgh Parliament, Scotland had massively turned away from Catholicism and evolved a Protestant, Presbyterian church founded in a rejection of church hierarchies. In August 1560, the Scottish parliament adopted a Calvinist Confession of Faith and during the second semester of the year 1560, a six member commission set up the new church known as the Kirk. The Church of Scotland adopted a Calvinist, Presbytero-synodal^[11] structure : bereft of bishops, it is organised around the congregations, its base communities, run by their ministers, deacons and elders and it sets up a range of hierarchical elected synods^[12] presided over by the General Assembly. From the 17^th century, Scottish Presbyterians migrated to Ireland not only to find land but also to proselytise.