David,
You ask what event forced your ancestors to leave Ireland. In general terms the answer will be economic betterment. Exactly the same drivers as motivate todays new immigrants to America or Australia or New Zealand.
The position in Ireland in the 1700s was that the population was growing significantly. The population rose from 3 million in 1741 to 8 million in 1841. (It?s only 6 million today). Rents were rising (for land they knew they would never own), there were some poor harvests, a decline in the linen industry, and for Presbyterians (and Catholics), there was some religious discrimination. People who were not Church of Ireland were prevented from holding public office or important posts in society. There were some restrictions on how they practiced their religion. Positive accounts from those who had already emigrated also influenced those remaining in Ireland. So all of these factors, plus news from north America that cheap/free land which could be owned outright could be had there, encouraged people to go. Some 200,000 people emigrated from Ulster to North America in the 1700s.
If you want to read the background in more detail, a good book is ?Eagles Wings ? The journey of the Ulster Scots and Scotch-Irish? by Dr David Hume.
According to that book (page 186), ?in 1774, 298 of 518 passengers from Belfast to Nova Scotia in Canada, interviewed on reasons for emigration, outlined that they had done so because of the desire to seek a ?better livelihood and employment.?
Also, the Presbyterian communal bloc was a factor:
?The strength and compactness of the Presbyterian bloc and the reality of the hold of the Presbyterian church over the daily lives of its members had an important effect?just as coals burn more brightly when in contact with one another, so did resentment rise among the closely knit and numerically dominant Presbyterian congregations in north east Ireland. If that resentment did not of itself produce emigration, it helped the waverers to make their decision and lived in many minds long after temporal hardships were forgotten. Emigration in such a community was likely to be as contagious as a fever in an insanitary town: it was liable to become a local epidemic if the minister sponsored it.?
Also on p 186, Rev James McGregor, a Presbyterian Minister in Coleraine in 1718 said in a sermon that ?his group was leaving for a number of reasons, these being to avoid oppression, to shun persecution, and to be enabled to worship God according to their consciences. Although his reasons were religious, others undoubtedly had material or commercial reasons for going.?
The reason that the British Government had imposed restrictions on Presbyterians and Roman Catholics was largely because they were seen as troublemakers who were likely to undermine a stable society. They had threatened rebellion and revolution, they might support a foreign invasion (by the Spanish or French) and so on. They were seen a little like Islam is seen in many western countries today. A serious threat to a safe society. There are parallels to be drawn between today?s extreme Islamic preachers who encourage jihad, and similar sounding Presbyterian Ministers who encouraged dissent and revolution from their pulpits. (In the United Irish rebellion of 1798, several of the leaders were Presbyterian Ministers who were subsequently executed for their treasonous behaviour).
As everyone knows, amongst other things, the 1st amendment to the US Constitution prohibits the making of any law respecting an establishment of religion or impeding the free exercise of religion. One of the drivers behind that amendment was the knowledge by US politicians (many of whose families were recent Presbyterian immigrants) of the difficulties their ancestors had faced in Ireland and the rest the British Isles, because of their religious beliefs.
Elwyn