Fritz Kolbe, an official at the German foreign ministry, turned over some 2,600 sensitive documents to the OSS in Switzerland during the latter half of 1943. Those files showed vice-president Henry Wallace had been talking indiscreetly to his brother-in-law, a Swiss diplomat, who had been passing on the information to his own foreign ministry, where it was falling into German hands.

As a result of the Kolbe documents, Wallace was dropped and replaced by Harry S Truman as Roosevelt’s running mate in the presidential election of 1944, and Truman succeeded to the White House within six months.

From the Irish standpoint Kolbe’s documents were equally alarming, at least initially. General William J Donovan, head of the OSS, told the White House “that a great deal of information pertaining to Allied activities in England and Ulster comes from the German embassy in Dublin. The legation, which is heavily staffed, has succeeded in infiltrating agents into England.”

The OSS reported, for instance, that German diplomats in Dublin had identified 600 air installations in England. Carter Nicholas, the head of the Éire desk at OSS headquarters, noted that it “looked to me at first as though there was a serious leak from Éire”.

When the OSS shared this information with its British counterpart — MI5 — the British explained that the reports from Dublin were part of a deception plan. MI5 had been feeding misinformation to the German legation. To ensure that the Germans would believe the various deceptions, the material was buried in a wealth of accurate information that the Germans already knew.

When MI5 explained the situation, OSS leaders realised the Irish security situation was even better than they “had previously thought”. MI5, which was effectively using the German diplomats in Dublin as double agents, had serious reservations about the Americans demanding the expulsion of Axis diplomats from Dublin.

If the German diplomats were expelled, MI5 warned that this would possibly endanger Allied security, because the Germans might infiltrate a useful spy. As it was, the British had broken the German codes and were reading all the messages from the legation in Dublin.

The OSS knew Gray’s proposal was just a political ruse, so it did not involve itself in the American Note, which was delivered to de Valera on February 21, 1944. News of the note and de Valera’s refusal broke on March 10.

As this was the week leading up to St Patrick’s Day, the news ignited a firestorm of criticism in the American press. Ireland was denounced as indifferent to the lives of American soldiers, even Irish-American boys. Some American journalists contended that the Irish should realise that diplomats were often used as spies.

The press campaign against Ireland turned so nasty the Irish feared the Americans might even divulge how the Irish diplomats were being used on the continent.

Carter Nicholas noted: “Walshe was very anxious about the point, particularly as the Irish could not publicly admit to having engaged in so unneutral an act as supplying us with anti-Axis intelligence.”

If the Americans divulged that Irish diplomats were being used as American spies, Walshe warned that all co-operation would be cut off.

“We would never dream of using any confidential information we could have got from your people,” a senior state department official assured Robert Brennan, the Irish minister in Washington.

Walshe suggested to the OSS that American and British security officials should be stationed in Ireland “to keep in constant touch with Irish authorities on the problems, to receive reports from them, and to make recommendations for improving methods of surveillance”.

As the American Note was strictly a political ruse, the OSS had initially tried to avoid involvement, but as the diplomatic tension was growing, General Donovan decided to outline the details of secret Irish security co-operation in a memorandum to President Roosevelt on March 30, 1944. He provided a long list of ways in which the Irish had been helping, and he emphasised the potential of the help being provided by Irish diplomats on the continent.

“So far the information contained in these reports has been of use primarily as confirmation of information from other sources,” Donovan explained. “However the potentialities are important.”

“The co-operation in intelligence matters offered and given by the Irish has been very full,” Donovan added.

“Since the delivery of the American Note the Irish offered their prompt cooperation in adopting whatever security measures may be recommended by us.”

GRAY tried to block acceptance of the latest Irish offer. He warned Roosevelt on April 14 that such co-operation could be used “as a political means of wiping off the record” the stigma of de Valera’s refusal to dismiss the Axis diplomats. “As long as we keep him hooked on his record of refusing our request he cannot do us any great harm either now or in the postwar period,” Gray insisted, “but he is very apt to catch us napping and wriggle off”.

All three OSS agents had been withdrawn from Ireland, but now, at the suggestion of the Irish, the OSS decided to station Ed Lawler in Dublin for the rest of the war. “The co-operation and information we received from the Irish was every bit as extensive and helpful as it would have been if Ireland had been a full partner with us in the war effort,” Lawler wrote.

For decades after, the intelligence co-operation provided by the Irish was played down. The first public indication of such help was R Harris Smith’s assertion that the Irish diplomatic corps smuggled espionage material out of Italy for the US in the Irish diplomatic pouch. This seemed to fit in with the secret co-operation provided by the Irish, but there was an added twist.

Irish diplomats on the continent were under instructions from early in the war not to transmit confidential material in diplomatic bags, because they knew the Germans were opening them. Thus, they would hardly have transmitted secret material for the OSS from the Vatican.

The Vessel Project supposedly originated when the Vatican’s acting secretary of state, Monsignor Giovanni Montini (later Pope Paul VI), offered the Americans strategic information in the form of reports from the Vatican representative in Japan. The whole thing was actually a scam run by a former journalist named Virgilio Scattolini, who had sold bogus Vatican information to various wire services before the war.

Following the liberation of Rome in 1944, he sought to reestablish this lucrative trade in forged documents.

The Vessel material was considered so good some of the raw material was shown to Roosevelt. But in February 1945 the OSS learned that Scattolini had embellished messages from the Vatican’s representative in Tokyo. The US had broken the Vatican code and was reading the original messages, so the fabrications were detected, but not before Scattolini had ripped off the OSS.

Montini’s name had been used to lure the OSS, which then used his name as Pope to cover up its own gaffe. In the early 1970s the OSS pretended that it had to keep the project secret in order to protect the Pope, and the Irish president.

Neither the Pope nor de Valera had actually been involved in the Vessel Project. The whole thing was a smoke screen to cover up the OSS blunder. It was, of course, just another of the many deceptions.

Historians who are unaware of MI5’s input in feeding the Dublin legation misinformation have perpetuated the myth that Ireland was the source of valuable information for the Germans.

* Ryle Dwyer’s Behind the Green Curtain: Ireland’s Phoney Neutrality during World War II, is published by Gill & Macmillan.