THE revelation of a secret plan for a Nazi invasion of Ireland during the Second World War, which was up for auction in England yesterday, should come as no surprise.

The declaration of Irish neutrality at the outset of the war was a determined assertion of Irish sovereignty and the culmination of de Valera's successful mission during the 1930s to win back the Irish ports of Lough Swilly, Bearehaven and Cobh, which Britain held under the terms of the Anglo-Irish Treaty. But neutrality also involved walking various diplomatic tightropes, and possibilities abounded about the violation of neutrality from both Germany and Britain, especially in 1940.

The trade-off for the return of the ports, and thus denial of Britain's access to naval facilities, was that Ireland was supposed to make sure it was not a threat to British security, which meant preventing third parties using Ireland as a means to attack Britain. This became a serious military and security preoccupation, for the simple reason that Ireland did not have the means to defend itself, despite the stirring rhetoric that the Irish would resist any invasion.

By June 1940 the situation in Europe had altered dramatically, once Hitler had decided to go on the rampage and Churchill had become British prime minister. The British dominions secretary, Malcolm Mac Donald, arrived in Dublin on June 17, 1940 talking up the possibility of a German invasion and offering Irish unity in return for the abandonment of neutrality, an offer rejected by de Valera.

Despite the plans for a German invasion, in some ways a British invasion was more likely, particularly in view of Churchill's refusal to accept the legitimacy of Irish neutrality; he referred dismissively to the "so-called neutrality of so-called Eire". It was certainly deemed a live possibility at the time.

And what of the Nazi plans in relation to Ireland?

After the fall of France in June 1940 southern Irish ports were vulnerable to German aerial attack; Hitler's forces could have pushed through Ireland with ease, in a country with no modern defensive aircraft or naval service. As the poet Patrick Kavanagh rather harshly put it, Ireland would be hard-pressed "to protect a field of potatoes from an invasion of crows", never mind the military might of the Nazis. The consequences would have been catastrophic.

Thankfully, none of this came to pass. Britain and Ireland became close in terms of security and military intelligence, with arrangements put in place so that in the case of a German attack there would be an agreed Anglo-Irish response which would involve an Irish attempt to hold the Nazis at bay for a few days before the British arrived to back them up. But another issue was whether Britain would have intervened first and therefore become the violators of neutrality.

BUT the bottom line in 1940, and up to the end of the war, was the Irish need to prevent invasion and preserve neutrality, and Irish diplomats went to considerable lengths to do that, often by conveying to London in the words of Joseph Walshe, secretary of the Department of Foreign Affairs, Ireland's "position of benevolent neutrality". Pragmatism was necessary given the, at times, very real threat of a German invasion, as underlined in the documents under the hammer yesterday, and as de Valera had recognised himself, absolute neutrality was a luxury Ireland could not afford, but there was to be continuing tension in the Anglo-Irish relationship throughout the war.

Dublin believed the immediate threat of a German invasion had declined by July 1940. Although no invasion occurred, it was not to be totally spared Nazi aggression. Two German aircraft dropped bombs in Wexford in August 1940, and there were sporadic attacks for the next nine months, culminating in the bombing of North Strand in Dublin in May 1941 that left 34 people dead.

Diarmaid Ferriter is Professor of Modern Irish History in UCD

Irish Independent