They came to the Americas and the West Indies as slaves. Vast numbers of human cargo, transported on tall British ships bound for the Americas.
They were transported by the hundreds upon thousands, and included men, and women of all ages, and even the youngest of children.
Whenever, or wherever they resisted, or rebelled, or disobeyed a command, they were punished using the harshest methods imaginable. Their owners would hang them by their wrists or ankles, and set their feet and hands on fire by way of chastisement. Many were burned alive, and their severed heads were placed on pikes in a prominent position in the local market place, as a warning to others who transgressed. 
Most of us are acutely aware, and even more so recently, of the atrocities that were committed during the African slave trade aren’t we?
But am I really talking about that here?
I could have been talking about the time when the English Kings, James II, and Charles I, led a continued effort to enslave a large section of the Irish population, could I not?
Or I could have been referring to a time when King James II sold 30,000 Irish prisoners, who were then sent to the New World, or I may have been talking about his 1625 proclamation, which required that Irish political prisoners be sent overseas, after being sold by auction to English settlers in the West Indies.
But I could not have been talking about any of that, could I?
If you submitted a Google search using the term ‘Irish Slave Trade’, for example, as most people often use that particular search engine, you will discover very quickly, that it’s a complete ‘Myth’, and as much as a myth as the claim that ‘Irish slave women and girls were bred with African slaves, to produce a new, cheaper generation of slaves’.
Wikipedia, for example, pulls no punches.
“Irish Slaves myth
This article is about the conflation of Irish indentured servitude and African chattel slavery.
The Irish slave myth is a pseudo history that falsely conflates the penal transportation and indentured servitude of Irish people during the 17th and 18th centuries with the hereditary chattel slavery experience of Africans. Some ‘WHITE NATIONALISTS’ and others who want to minimise the effects of hereditary chattel slavery on Africans and their descendants, have used this ‘false equivalence’ to promote RACISM against African Americans, or claim that African Americans are too vocal in seeking justice. The Irish slaves myth has also been invoked by some Irish activists, to highlight the British oppression of the Irish people and to suppress the history of Irish involvement in the transatlantic slave trade. The myth has been in circulation since at least the 1990s, and has been disseminated in online memes and social media debates. In 2016, academics and Irish historians wrote to condemn the myth.”
Wikipedia are not the only mainstream source that promotes the idea of Irish slavery being a myth, as most other mainstream sources, inc., the media, academia and historians, as well as the teaching profession, take a similar stance.
They utterly refute the claim that from 1651 to 1660, there were more Irish slaves in America than the entire [non-slave] population of the colonies. 
They also pour scorn on the claim, that Ireland was, at one point, the largest source of human livestock for English slave merchants, and that the greater majority of slaves that were initially sent to the New World, were white Irish men, women and children.
They are of course, not willing to discuss, that from 1641 to 1652, over 500,000 Irish people were killed, and a further 300,000 were sold into slavery, and would also argue that the population of Ireland did not fall from around 1,500,000 to 600,000 in a single decade.
The possibility that Irish families were being ripped apart, as the British did not allow Irish men who had children, to take their wives and children with them across the Atlantic, which led to a mostly helpless Irish population consisting of homeless women and children, would also be denied.
And the mere suggestion that those women and children who were left behind, were later sold as slaves, and sent overseas too, would be unthinkable.
So, all things considered, most people today, under the guidance of the mainstream media, tame historians, academics, schools, colleges, universities, Google, and Wikipedia, etc., would not, ever consider referring to Irish people who had been affected, as what they really were.
They use terms like ‘indentured servants’ instead, to describe what went on, but it matters not what words, or definitions are used, the truth is, that in most cases, between the 16th and 17th centuries, hundreds upon thousands of Irish men, women and children were treated as little more than human cattle.
“In 1655, Cromwell sent British Admiral Penn and Admiral Venables on an expedition to conquer Santo Domingo from the Spanish. They were not successful. Instead of returning home completely empty-handed, they sought to conquer Jamaica, which had weaker defences. Reinforcements from British-owned Barbados, which included many Irish slaves, supported them in the effort, giving England one more conquest. Cromwell, with his new island, had Irish slaves sent from Barbados and St Christopher to work the new land. Jamaica went on to become the centre of the English slave trade in the Caribbean. Henry Cromwell, the court-oldest son of Oliver Cromwell, was Major-General of the forces in Ireland. Henry was subordinate to the Lord-Deputy Charles Fleetwood, but when Fleetwood left for England on business, in September 1655, Henry became de facto ruler of Ireland. On September 11, the following decree came from him: ‘Concerning the young [Irish] women, although we must use force in taking them up, yet it beinge so much for their own goode, and likely to be of soe great advantage to the publique, it is not in the least doubted, that you may have such number of them as you think fitt to make use uppon this ac-count. [The ‘ac-count’ was enslavement and transportation to Jamaica and Barbados]. A week later, Cromwell ordered that 1,500 Irish boys, between the age of 12 and 14 also be shipped into slavery in Jamaica and Barbados. In October, the Council of State approved the plan. Many of the boys did not survive this ordeal. Just as thousands of adults died labouring long days in the steaming heat of Barbados, the children succumbed to the same fate.” – Byrd, Herbert L. Proclamation 1625: America’s Enslavement of the Irish (2016)
As a comparison, the African slave trade from Africa was only just beginning during that period, and it is well documented, that African slaves, not ‘tainted with the stain’ of the detested Catholic theology, were more expensive, and were often treated far better than the Irish.
(Irish Catholics were not considered Christians, even if they were free men.)
African slaves were very expensive to purchase during the latter part of the 1600s, on average being sold for around fifty pounds, while an Irish man or woman, could be purchased at auction for as little as five pounds.
Children were often cheaper.
If a planter whipped, or branded, or beat an Irish slave to death, it was not even classified as a crime. A death was merely a setback in monetary terms only, but it was still a cheaper option than killing a more expensive African slave.
All the children that were born to Irish slave women and girls, became the property of the plantation owner, which increased, not only the size of their workforce, it also kept their costs down.
Even if an Irish woman had somehow obtained her freedom, her children remained the property of the plantation owner, which in most cases, meant that many Irish mothers, despite being freed, refused to abandon their children, and would remain in servitude.
As time passed, another barbaric practice became commonplace, and is the most hotly disputed claim of them all, which was that plantation owners bred Irish female slaves (in many cases they were girls as young as twelve), with African slaves, in order to produce children with a distinct complexion.
That practice came about, because in 1662, the Virginia ruling class established the ‘partus sequiter ventrem’, a law which defined the free, or slave status of a newborn child, based on the status (free/slave) of its mother.
“The offspring follows the mother; the brood of an animal belongs to the owner of the dam; the offspring of a slave belongs to the owner of the mother, or follows the condition of the mother. a maxim of the civil law, which has been adopted in England in regard to animals, though never allowed in the case of human beings.”
If the mother was a slave at the time of the birth, then the baby was a slave, and became the property of the slave owner. If you were European and your mother was a slave, you were also a slave. If you were African, and your mother was free, then you too were free.
That law remained on the statute books for 143 years.
However, once that law had been passed, the slave owners came up with a tactic that would produce African slaves – or something very close – but without the high cost of purchase.
They began to breed the African males with the Irish women and girls, which produced free labour, that they could either use themselves, or sell to others at a profit.
These new ‘Mulatto’ children, commanded a far higher price than their mothers, and enabled their owners to save money on the purchase of expensive African slaves.
That practice went on for decades, and became so widespread, that in 1681, legislation was passed ‘forbidding the practice of mating Irish slave women to African slave men for the purpose of producing slaves for sale.’
In other words, it was only outlawed, because it ate into the profits of the large slave trading companies.
England continued to ship thousands of Irish men, women and children overseas for more than a hundred years, and records show, that following the 1798 Irish rebellion, thousands of Irish men, women and children were sold into slavery to the Americas, and also to Australia.
There were of course many horrible abuses visited on slaves, notable examples, being the Zong Massacre in 1781, where more than 130 enslaved Africans were murdered by the crew of the British slave vessel ‘Zong’, and the ‘dumping’ by the British, of 1,302 African slaves into the Atlantic Ocean, so that the crew had enough food to survive the crossing.
However, there is little question that the Irish experienced the horrors of slavery as much, (if not more during the 17th century) as Africans did.
There is, in addition, little argument against the fact that those tanned faces you may see on holiday in the West Indies, are highly likely to be a combination of African and Irish (Slave) Ancestry. 
ADAPTED FROM: THE FORGOTTEN WHITE SLAVES
 ‘They revolted, but their revolt was contained, and severe punishment was imposed on the Irish slaves. Plantation owners on the island employed English statutory penalty first enacted by King Edward III in 1351: the slaves were hanged, drawn and quartered – a punishment usually reserved for men found guilty of high treason. The victim was fastened to a wooden panel and dragged by a horse to the place of execution, where they were then hanged (almost to the point of death), emasculated, disembowelled (had some of the organs of the gastrointestinal tract removed), beheaded, and quartered (chopped into four pieces). In England, the traitors’ remains were often displayed in prominent places across the country, such as the London Bridge. The slave owners placed the heads of the executed slaves on pikes, prominently displayed around Bridgetown as a warning to others.’
 “By the mid-1600s, a high proportion of the working population in Barbados were Irish. Some of what we know of the population of the Irish in the Indies and their condition, comes from the priests who travelled to minister to them. According to father John Grace, 12,000 Irish lived in Barbados and surrounding islands. he also reported 600 Irish slaves in the small island of St. Christopher”. – Herbert L. Byrd. Proclamation 1625, Americas’s enslavement of the Irish (2016).
 “Truly I have seen cruelty there done to servants as I did not think one Christian could have done to another. To end the barbarity that was was being inflicted upon the Irish slaves, a Colonel William Brayne wrote to English authorities in 1656, urging for the importation of Negro slaves, on the grounds that as the planters would have to pay much more for them, they would have an interest in preserving their lives, which was wanting in the case of [the Irish], many of whom, he charged, were killed by overwork and cruel treatment”. – Ligon, Richard – A True and Exact History of Barbados (2011).
 ‘The Irish and African slaves remained in Barbados until the British abolished slavery in 1833, many of the descendants of the children of the Irish and African slaves are still there’ – Herbert L. Byrd. Proclamation 1625, Americas’s enslavement of the Irish (2016).