The Brexit crisis represents incomparably the greatest challenge for Irish foreign policy since the second World War, the only global crisis since the establishment of the Republic in 1937-38 that has seriously threatened our pursuit of an independent foreign policy.
Although there is now no threat of war this, too, is a great European crisis with global ramifications.
There is another similarity: although in theory Eamon de Valera publicly implemented a policy of neutrality evenly upheld between the warring blocs, in practice he secretly did everything he could to ensure that Britain won the war so long as he could do so without overtly compromising that policy of neutrality.
Ireland’s national interest, he correctly concluded, demanded nothing less.
Brexit poses a comparable dilemma. How can we reconcile a recognition of all that binds our national interest so closely to the interests of Britain with our reputation as good Europeans?
In 1961, when the Lemass government first applied to join the Common Market, such was the predominance of the British market for Irish producers that when General de Gaulle vetoed the British application in 1963 the Irish application was simply allowed to lapse. When we finally joined the EEC in 1973 we did so hand in hand with the British.
Since then, our paths have diverged because we have never shared Britain's semi-detached attitude to Europe - notably when we established an independent currency and joined the euro zone while the British remained outside.
But not until now have we been called upon to make so stark a political choice. Taoiseach Enda Kenny’s Government was right to do all they could to support David Cameron’s campaign to remain in the EU. But the decision of the British people to choose Brexit changed everything.
Mr Kenny's statement after the emergency Cabinet meeting on Friday morning was reassuring because it clearly recognised the new reality. Yet what was arguably the most significant foreign policy statement by a Taoiseach since we joined Europe has not received the coverage it warranted, especially from RTÉ, which chose instead to highlight the jingoistic rantings of Nigel Farage in its news bulletins.
Plan B
The essence of what Mr Kenny said was that "Ireland – as a committed member state of the EU – will work within the EU context. At the same time, Ireland has unique bilateral interests with the UK, including with regard to Northern Ireland, and the Government will also have to work bilaterally in close contact with the UK government and the devolved Administration in Northern Ireland."
Also reassuring was the revelation that the Government already has a plan B in the shape of a contingency framework identifying the key issues, endorsed by the Cabinet on Friday. These are spelt out in an elaborate eight-page appendix to Mr Kenny’s statement.
So far so good, but it remains to be seen if the pieces of a complex jigsaw will be put in place with a regretful but relentless determination to put the national interest above all considerations of amity with Britain.
The final sentence of the appendix offers comfort in this regard: that during the negotiation of the Brexit process, “the Government will monitor and intervene proactively in relation to any attempts to further deepen EU integration (EMU) defence and security”.
Harmonious departure
Although the EU may identify with German chancellor Angela Merkel’s insistence that Britain’s departure must be engineered as harmoniously as possible, it simply cannot afford to offer terms so generous that they will invite other members contemplating exit to follow suit. That would mean the collapse not just of the euro zone but of the EU.
Jean-Claude Junker, the president of the European Commission, sounded a more realistic note when he predicted that it "won't be an amicable divorce but it wasn't a great love affair anyway . . . If someone complains about Europe from Monday to Saturday, you will not believe them if they say they are good Europeans on Sunday."
The founding members of the European enterprise are already circling the wagons.
On Saturday, the foreign ministers from the countries that comprised the original European Community met in the residence of the German foreign minister and issued a statement stressing the need to begin the Brexit negotiations as soon as possible and the importance of now focusing on the future of Europe.
Peter Sutherland, much the most impressive of all Ireland's European commissioners, who now lives in London and has not an Anglophobic bone in his body, went to the heart of the matter in his interview with this newspaper on Saturday.
Brexit must have consequences “because if there were no consequences you might as well dissolve the EU tomorrow”.
Ireland’s strategic priority must be “to stand four-square with other EU member states . . . From an Irish perspective, the biggest disaster . . . would be irreparable damage to the EU itself.
"Our only strategy," he said, "economic and political, has to be reinforcing the European Union and being part of the inner core of that European Union."
For Sutherland, a keen rugby player in his youth, this was the political equivalent of Ireland’s Call.
Mr Kenny must sing the same tune when he goes to today’s European summit because that is when the leaders of the other EU states will decide if he is as good a European as he protests. Ronan Fanning is Professor Emeritus of Modern History at UCD