Ireland was neutral in WW2. While there were some (I don't have any idea how many) Irish who detested Britain enough to be active supporters of the Axis, there were some who were active supporters of the Allies, in opposition to the Axis. It probably didn't help Germany's position in Irish eyes as there were several bombing raids that struck Ireland, including Dublin.
Throughout the summer of 1940, Britain saw Ireland as a potential threat to her security. Eire was still technically part of the British empire at this time, but, unlike the other Dominions, her strongly nationalist government under Eamon de Valera, Ireland's Taoiseach, refused to back the Allied cause. On the contrary, Ireland adopted a stance of overt neutrality, reflecting her determination to assert her independence from Britain.
More importantly, in the context of the Britain's defences, in 1938 the Irish government took control of the three deep-water naval ports, one in Donegal and two in County Cork, that Britain had retained under treaty. As the invasion threat deepened in 1940, the British authorities grew increasingly concerned about the presence of an uncooperative Ireland on their western flank*. Some leading politicians, including Churchill, saw a graphic contrast between the staunch loyalty of Protestant Ulster, under the veteran prime minister Lord Craigavon, and the sullen hostility of Eire, under de Valera. Anger at the loss of the treaty ports was compounded by the belief that southern Ireland was riddled with Nazi sympathisers, fifth columnists and IRA terrorists who adhered to the traditional doctrine that 'England's difficulty is Ireland's opportunity.'
In fact the British were quite wrong about this. De Valera was never hostile to Britain's cause as his critics suggested, claiming that he
'personally had great sympathy for England and recognised that two-thirds of the Irish population were anti-German'. Moreover, since the mid-1930s his government had pursued an increasingly ruthless campaign against Republican extremists, who were regarded as a dangerous threat to the nascent state. Not only was the IRA banned but its members faced internment, military tribunals and even executions. Yet the political reality was that, after decades of the Irish struggle for freedom from British rule, there was little chance that Ireland would join the other Dominions in fighting for Britain.
Neutrality was effectively an affirmation of sovereignty, and any declaration of war would have torn apart the fragile unity of the nation.
So what did ordinary Irish people do in the face of Nazism? Total figures on Irish volunteers and war workers remain uncertain, but the number of 'new travel permits', identity cards and passports issued to men and women in 1940-1945 was in the region of 200,000. To this should be added the 45,000 which the Department of External Affairs estimated went to the UK between September 1939 and the fall of France in June 1940, after which restrictions were imposed. In other words, out of a total population of approximately 2,968,000 (1936 census), over 8 per cent emigrated during the war. This is all the more significant when it is appreciated that those living in agricultural areas and all those under twenty-two years of age were prohibited from leaving the state, except in exceptional circumstances. If those under fourteen and over sixty-five are excluded, the figure rises to over 13 per cent and if we factor in the restrictions on those under the age of twenty-two, the number who travelled may have been well over 15 per cent of the eligible population.
Most Irish people wanted a unified Ireland. Few wanted a unified Ireland under a German jackboot.
My bold, it is the most pertinent point, in the context of which Irish neutrality must be understood.
*The Wehrmacht had no comprehensive plans to invade Ireland. General Günther Blumentritt, the operations officer of Army Group A, later explained that any thoughts about an early German landing in Ireland
'were quite unreal and they bear no relation to German resources at sea and in the air at the time'.