The Celts arrived in Ireland beginning in 600 BC and soon after, the island was divided into nearly 150 petty kingdoms called “Tuaths”, ruled by minor kings, which were in turn subject to more powerful kings who ruled groups of Tuaths and who were in turn ruled by five provincial kings.

The Irish culture developed over the next millennia into a largely agrarian society with no large towns or cities. Societal organization was described and regulated by Brehon Law drawn from centuries of teachings by kings and tribal leaders. Brehon law regulated societal conduct through precedents, which were established at a triennial conference called a "Feis Teamhrach", or Great Fair.

In 800 AD, Ireland was invaded by Viking Norsemen who plundered the country-side until 1014 BC when they met defeat at the hands of Brian Boru, future king of Ireland and leader of the Gaelic race.

The Normans appeared in Ireland in the tenth century and thus began the English domination of Ireland and the Irish people. By the late thirteenth century, England’s Henry VII took complete control by placing Ireland under English Law. Henry VIII stripped the Norman-Irish Earls of Kildare – wealthy landed gentry and de-facto leaders of Ireland - of their power in 1534 and had the Irish Parliament declare him King of Ireland.

English Protestant settlers began to populate Northern Ireland in the fifteenth century and eventually vastly outnumbered Catholics.

After Henry VII’s death, his children, Edward VI, Mary I and Elizabeth I continued to try to increase English control in Ireland and to convert the Irish to Protestantism by seizing land and awarding it to English settlers to Ireland and executing Priests and Bishops. These efforts only resulted in unifying the Irish people against English rule. Over the next sixty years, revolts in Ireland lead to Oliver Cromwell decisively crushing the Irish rebellion in 1650. Instead of the freedom they sought, the ultimate result of the rebellion was decimation of the Irish population,  “estimates of between half and two-thirds of the Irish population were said to have died through war, disease and starvation.”

In addition, strict anti-Catholic laws were introduced that prevented Catholics from holding public office, joining the army, attending schools or holding religious services.

James II gained the English throne in 1685 and abolished many of the Anti-Catholic laws. He was deposed by William in 1688, fled to Ireland and organized an army to regain his throne. In 1690, William’s experienced soldiers aided by Ulster Protestants defeated James II’s largely untrained Catholic army at the river Boyne in Northern Ireland.

By the beginning of the 16^th century, 90 percent of the land in Ireland was owned by English nobles to whom the Catholic tenant farmers were forced to pay rents. The turn of the century also saw the passage of penal Laws aimed at Catholics in Ireland. These laws included:

In 1800, despite great opposition, the Act of Union was passed by both the Irish and British parliaments. It was signed by George III in August 1800 to become effective on 1 January 1801. The Act of Union proclaimed:

For many in Catholic Ireland, the Act of Union was the final and ultimate insult. English landlords realized greater profits could be made from their land by grazing cattle and sheep and sought to evict tenants by any means possible. Rents became exorbitant and many Irish farm families found themselves literally thrown out on the street.

Revolts and protests occurred throughout the Catholic sections of the country in response to the growing number of poor and homeless. The English crown firmly believed the Irish people incapable of self-rule and exploited the Island colony. Leaders of parliament believed in political economy, market forces were sacrosanct such that legislation was unjustified unless it answered a clear need. There were only rumors of trouble in Ireland, which gave them license for inaction. Population theorist, Reverend Robert Malthus, who never actually visited Ireland, wrote: “the land in Ireland is infinitely more peopled than anywhere else; and to give full effect to the natural resources of the country, a great part of the population should be swept from the soil.”

Such attitudes were commonplace in England. The Irish were considered lazy, inept, alcoholic and tended to over-produce offspring. Doctrine such as Malthus’ believed disaster in Ireland was inevitable, and although it remained largely unspoken, desirable.

Across the world, in the uplands of Mexico, 1845’s crop of potatoes was not the best the natives had seen in years past. Many of the tubers had rotted in the ground. What was left of the harvest were either used locally or sold, packed in burlap sacks, and shipped to distant lands. One lone potato, lost in the hold of a north American ship and inadvertently transported to Europe set the stage for an agricultural disaster that triggered the migration of millions of Irish immigrants to various parts of the world.

“Phythophthora infestans is a late blight pest that has a complex life cycle and can attack potatoes (and tomatoes) in several ways. The assault usually begins when airborne spores land on the foliage and either germinate directly or release swimming zoospores. In either case, the pathogen penetrates the leaf or stem and grows into a dark lesion that releases thousands of new spores. Carried by wind or rain-splash, the spores can infect the same or other plants, sometimes miles away. Zoospores can be washed from the foliage to the potato tubers in the soil, causing them to rot immediately or in storage. Infected seed tubers can start a new cycle of infection in a following season.”

Irish agriculture at the time was of three distinct categories: Eastern farmers grew cereal crops while northerner’s grew flax. On the small farms in western Ireland grew potatoes. When the blight struck the country, 30% of the Irish people were largely dependant on the tubers for their daily sustenance. “Between 1845 and 1855, the prophesied ‘Destruction’ of Ireland became a reality. From the summer of 1845 through the early 1850’s, every harvest of potatoes – practically the only food for most of the island’s inhabitants – failed totally or partially, resulting in perhaps a million deaths...”

While many died of starvation, malnutrition-related diseases such as dysentery, scurvy and Cholera spread rapidly and were typically fatal due to poor nutrition; damp conditions and overcrowding in closely packed western Ireland.

Social conditions also contributed to the number of deaths in these years. The British were contemptuous of the Irish people, ownership of land was severely fragmented and the income gap between rich and poor was enormous. Both of these factors lead to squalid living conditions for the lower classes.

Great Britain initially responded to the emergency by removing a ban on grain imports and creating public works jobs for destitute farmers and laborers but London soon tired of the situation and washed its hands of the problem. “Irish colonialism’s most lethal legacy was a predominately alien landlord class which, despite individual instances of benevolence, did little to alleviate and much to exacerbate the crisis”. Nearly half a million people were evicted from their homes between 1846 and 1855 largely to facilitate the landlords trend from tillage to pasture farming which reduced the need for labor and freed land previously occupied by tenant farmers. Between 1845 and 1851, landholdings above 30 acres increased by 16.5% while landholdings less than one acre decreased by nearly fifty percent.

Food riots became common, as did theft of foodstuffs, which typically resulted in draconian punishments such as deportation to Australia. Add to this voluntary emigration to America (1.5 million), British North America, (340,000) and Great Britain, (2-300,000), in all about 2.1 million people, about one-quarter of the population of Ireland left in just eleven years – more than during the preceding 250 years.

Sadly, running from poverty, disease and hunger did not guarantee continued existence. Nearly 30 percent of those bound for British North America, and nine percent bound for America perished during the passage or shortly after arriving. Some were able to finance the passage through crop or livestock sales, some were aided by benevolent landlords but the majority were “brought out” by relatives in North America. Remittances to Ireland totaled in excess of 1.2 million pounds sterling annually.