The first phase of immigration took place between 1630, more than a century before the US became an independent country, and the time the American Revolution, which started in 1776. Beginning in the 16th century, the English began sending settlers to Ireland, many of them from Scotland. These as you know were known as the Scots-Irish.

England had separated from the Catholic church in the 16th century and formed the Church of England. Most of the native Irish people were Catholics, and most of the Scots Irish were Presbyterians, that is, they belonged to a Protestant church other than the Church of England. Under Queen Anne (1702 - 1714) the Presbyterians in Ireland became by the Test Act of 1704 virtually outlaws.

Their marriages were declared invalid and their Churches were closed. They could not maintain schools nor hold office above that of a petty constable. Reason enough to leave was that the Presbyterians could practice their religion freely in Ulster.

Another reason was the digest of atrocities committed by Irish Catholic rebels against Protestant settlers, such as the earlier massacres of 1641 in which an estimated 200,000 Protestants were murdered, its little wonder the Scotch Irish left for the new world with such vigor.

This ia an artists impression which depicts the 1641 massacre of Protestants by Catholic Rebel's over the River Bann in Portadown Northern Ireland.

A detailed analysis of 1641 can be found here

The Massacres were clearly planned, and on 23rd October 1641 the Irish Papists, led by Sir Phelim O'Neill, incited, encouraged, financed, aided and abetted by the Roman Catholic Church, its priests and hierarchy, rose up in an insurrection, the sole purpose of which was the total eradication of Protestants and Protestantism throughout Ireland . Its interesting to note that one of the leaders, P O'Neill is the name that the IRA use today to verify acts of terrorism, or which in correspondence with the media.

The following extract comes from Henry Jones’ Remonstrance of Diverse Remarkable Proceedings Concerning the Church and Kingdom of Ireland (1641). Published as a petition to Parliament on the eve of the English Civil War, it contains a digest of atrocities committed by Irish Catholic rebels against Protestant settlers of which this is a small section.

"But what pen can set forth, what tongue express, whose eye can read, ear hear, or heart, without melting, consider the cruelties, more than barbarous, daily exercised upon up by those inhumane, blood sucking tigers! Stripping quite naked men, women and children, even children sucking upon the breast, whereby multitudes of all sorts in the extremity of that cold season of frost and snow have perished. Women being dragged up and down naked, women in child bed thence drawn out and cast into prison… a child of 14 years of age taken from his mother, in her sight cast into a bog pit and held under water while he was drowned"

As well as political discontent, this first movement of emigration also had economic causes. The majority of Ulster Presbyterians were poor small holders, artisans, weavers and laborers, and these were most vulnerable both to the succession of natural disasters - crop failures, smallpox epidemics, livestock diseases - these recurred throughout the eighteenth century, and to the increasing commercialization of Ulster, with the constant efforts of landlords to increase the profitability of their lands by raising rents.

The increasing importance of the linen trade was also influential, and the numbers of emigrants rose and fell as this trade prospered or faltered.

In 1660 Charles II, son of Charles I, was restored to the English throne. Little changed for the persecuted Presbyterians. In the 1680's Charles II dispersed their congregations and invalidated their marriages. Married couples were dragged before ecclesiastical courts and charged with fornication; their children were declared illegitimate. The Presbyterians lost all their property to the Church of England. Ulster Scots again began to emigrate. In 1685 Charles II died, James II, a Catholic, then became King. James II tried to turn Great Britain into a religious state in which only Catholicism could be practiced. In 1689 he tried to recapture the throne by marching an army of Catholics into Ulster.

They laid siege to the fortress city of Londonderry. Protestants were shot in their homes, women were tied to stakes at low tide, so they might drown when the ocean waves came back. The army which besieged Londonderry was fought off with a desperation. The Ulstermen had no trained army officers, were without sufficient food or ammunition, and faced deadly fevers, yet the invaders were beaten off. James' bid for the throne failed and he was succeeded by William of Orange. James' downfall became known as the "Glorious Revolution," as it spared Presbyterians almost certain massacre. However, persecution continued. Presbyterians were not allowed to sell religious books, teach anything above primary school, and in 1704, Presbyterians were barred from holding major civil and military offices. Presbyterian minister, William Holmes, returned from America with encouraging news that the New England colonies offered refuge to Presbyterians.

In 1718, Governor Samuel Shute of Massachusetts encouraged the Scotch-Irish families to scrape together their savings and head for the New World.

Meanwhile the Church of England, which now owned all the lands, continued to pile indignities upon the Scotch-Irish. Presbyterian farmers paid excessive rents and then had to use their profits for tithes (donations to the church). The reasons to emigrate from the Ulster region multiplied. Crop failures in the 1720's, famine in 1741, farm rents soared in the 1770's, and the Ulster linen industry collapsed in 1772. And so begin the emigration. The very nature of the business facilitated emigration, since the ships which brought flax seed from America often returned with a cargo of emigrants. Before 1720, the stream of migrants across the Atlantic was steady and almost exclusively Protestant. After that date, the rate of emigration grew, with a peak in the late 1720s, and a decline in the 1730s, when relative prosperity returned to Ulster. The famine of 1740-1741 gave a sharp impetus to the renewal of emigration, which rose steadily through the 1760s, when more than 20,000 people left from the Ulster ports of Portrush, Belfast, Larne and Derry.

The migration reached a climax in the years 1770 to 1774, when at least 30,000 people departed. Over the course of the whole century, it is estimated that more than 400,000 emigrated from Ulster, the vast majority to North America; in 1790, the number of the United States population from Ireland North and South has been estimated to have been 447,000, two-thirds of which were Ulster's Scotch Irish. The Irish rebel's openly and avowedly rejoiced at this impending calamity and use all means and artifices to encourage and persuade the Protestants to leave the nation, and cannot refrain from boasting that they shall by this means have all the lands of this kingdom in their possession.

One important result, significantly different from later Catholic emigration, was the fact that the Scotch Irish move was often carried out by entire families and even communities, allowing the settlers to maintain their way of life in the new world, and providing a continuity of religion and tradition in keeping with the religious and cultural separateness they had already brought with them from Northern Ireland.

The influence of their culture, their music, religion and way of life, can still be seen in the US today. The blend of Protestant evangelism, fierce self-sufficiency and political radicalism that many Ulster Presbyterians brought with them to the New World, was powerfully influential in the American Revolution.

In all of the states, but especially in Pennsylvania, New Jersey, New York, Delaware and Maryland, the immigrant Scots-Irish and their descendants played a role in the war out of all proportion to their numbers; as an officer on the British side put it,

"call this war by whatever name you may, only call it not an American rebellion; it is nothing more or less than a Scotch Irish Presbyterian rebellion".