According to a medieval Irish chronicle, the first Jews to come to the island arrived in 1079 but were promptly turned away. Only in the 19th century did Ireland gain a significant, if always small, Jewish population. Aidan Beatty and Dan O’Brien write:
At its demographic height, [just after World War II], the Irish Jewish community numbered about 4,000; one tenth of 1 per cent of the total population of Ireland (north and south). Hardly a major aggregate. And yet, at that time, Jews were the only sector of the populace whose origins lay outside of Britain and Ireland; the community had long been a noticeable presence in Dublin. In 1908, for instance, the charter meeting of a Judeo-Irish Home Rule Association . . . was the cause of noticeable controversy in Ireland and within the British Jewish community; should Irish Jews remain a loyal subset of their co-religionists on the other side of the Irish Sea or should they throw their lot in with nationalists [in Ireland]?
A desire to prove their nationalist bona fides and thus to prove that they are “real” Irish would endure within the Irish Jewish community. And the community’s official narratives have often downplayed the existence of anti-Semitism among Irish Gentiles.. . .
Some of the most central figures of 20th-century Irish life have been overt anti-Semites. . . . Anti-Semitic rhetoric and imagery regularly surfaced in the nationalist press before and after 1922. The IRA-backed campaign against usury in the late 1920s targeted Jewish moneylenders far more than their Gentile counterparts. Jewish industrialists who fled the Nazis and established factories in the west of Ireland in the 1930s and 40s often had to negotiate a matrix of stereotypes and negative perceptions. The sizeable numbers of Irish men who served in the Palestine Police in the same period regularly interpreted what they saw in Jaffa, Jerusalem, or Bethlehem in terms of the anti-Jewish animosities traditional to Catholicism.
Read more on Irish Times: https://www.irishtimes.com/culture/books/ireland-s-complex-jewish-history-influential-figures-who-were-anti-semites-1.3671755