The conflict between Catholics and Protestants in Ireland began in the 1530s. As Protestantism would emerge as the ruling group, many Catholics left for sympathetic Catholic countries on the Continent. Those who fled were termed “Wild Geese.” However, Protestants also followed.
Many date this immigration to 1607 and the “Flight of the Earls” after the Irish defeat at Kinsale. However, out migration was already under way. Estimates are that between 1585-1625, some 10,000 Irish Catholics fled to the Continent. Another wave occurred after the Protestant Cromwellian victory of 1649-1651. A particularly high period of out migration occurred between the Treaty of Limerick (1691) and the Peace of Aix-la-Chapelle (1748), with an estimated 50,000 left. Most would go what is now Austria, France, Portugal and Spain. Others would go to a lesser degree to Eastern and Central Europe and the Papal States (now Italy).
Both rich and common people left, in a strange mix of Catholics and Protestants. They would live and intermarrying with each other on the Continent; doing what they could not do back in Ireland. They can be divided into four groups: 1) soldiers and officers in continental armies, both Catholic and Protestant; 2) Catholic gentry and nobles who fled Protestant Ireland; 3) merchants both Catholic and Protestant, and 4) Catholic priests and seminarians studying in colleges.
Many works document these migrations. A classic text is Matthew J. Culligan and Peter Cherici’s The Wandering Irish in Europe: Their Influence from the Dark Ages to Modern Times (1999). The “Irish in Europe Project”: www.irishineurope.com seeks to document this fascinating piece of Irish history.
Due to the early migrations of these families, don’t be surprised if your nineteenth century French or Spanish immigrant to North America were actually Irish!