Consequential as it became to the course of modern Ireland, Éamon de Valera's escape from execution after the Easter Rising still evokes mystery as an enduring dimension of its history.

What exactly was the reason for de Valera's reprieve?

Was it the fact that he wasn't a signatory of the Proclamation and didn't fight in the General Post Office?

Was it the lateness of his court-martial amid the mounting criticism over the deadly policy of reprisal?

Was it the circumstance of his birth in the United States at a time when Great Britain was trying to cultivate a closer relationship with the increasingly influential nation?

A search of de Valera's papers (now housed at the Archives of University College Dublin), documents at the UK's National Archives at Kew and numerous other primary or secondary sources lead someone in different directions before reaching a conclusion.

For example, de Valera's American ties are often cited as a principal factor in the British decision to reverse his death sentence. His wife Sinéad certainly tried to play this card, and stories circulated in US newspapers that his American heritage proved decisive.

The Boston American on July 9, 1916, published an article with this headline: 'Citizenship in US Saved Valera's Life.'

Complete with the mistake in the surname, this news account and two others saying the same thing are included in de Valera's papers at UCD.

The origin of the information is never reported and not rebutted until many years later. It's little wonder that for the better part of de Valera's six-decade public career, his birthplace kept coming up as playing a role in his commutation.

As late as 1963, de Valera himself didn't hesitate to retell the story of his reprieve by emphasising his roots in another country.

During John F Kennedy's only trip to Ireland while US president, he became the first foreign head of state to honour the Rising's executed leaders at Arbour Hill Cemetery.

Later, according to their book Johnny, We Hardly Knew Ye, Kennedy aides Kenneth P O'Donnell and David F Powers report that during their last night in Ireland, the American party attended an informal dinner with de Valera at which (in their description) "the conversation was sparkling and the laughs plentiful".

But Kennedy could not resist asking de Valera one specific question. Why had he not been shot in 1916?

"De Valera explained that he had lived in Ireland since his early childhood," we're told, "but he was born in New York City, and because of his American citizenship, the British were reluctant to kill him. 'But there were many times when the key in my jail cell door was turned,' he said, 'and I thought that my turn had come'."

This account notes that Kennedy "listened, spellbound".

Was de Valera, then 80 and President of Ireland, trying to impress the young Irish-American leader in a politically ingratiating manner? Did he know otherwise at the time?

Such questions arise because six years later, de Valera's story officially changes. In 1969 (and now in his second term as president), he took up paper and pen to draft a personal statement, which included this declarative sentence: "The fact that I was born in America would not have saved me."

A document with the heading 'Reprieve of Éamon de Valera' was prepared on July 3, 1969, and printed on presidential stationery. It incorporated phrases and sentences that de Valera had crafted, amplifying some along the way. The key sentence - "The fact that I was born in America would not have saved me" - became "The fact that I was born in America would not, I am convinced, have saved me" in the official version.

The first point de Valera makes is definite: "I have not the slightest doubt that my reprieve in 1916 was due to the fact that my court-martial and sentence came late."

The last paragraph in the official statement, not a word of which appears in de Valera's handwritten composition, returns to the timing of his case: "By the way, Thomas Ashe was court-martialed the same day that I was. He, too, would have been executed, I have no doubt, had he been tried earlier... He was not an American citizen, and it could not be suggested, therefore, that it was on that account he was reprieved."

How sensitive had de Valera become to the suggestion that his American roots were involved in his corporal salvation? The year after his 1969 explanation, the authorised biography Éamon de Valera by the Earl of Longford and Thomas P O'Neill was published.

In retelling how the aftermath of the Rising unfolded, the authors note: "Two commandants escaped the firing squad because of the delay in bringing them to trial. They were Thomas Ashe and Éamon de Valera. It has been suggested that the latter was reprieved because of his American birth. There is no evidence of this, and the fact that he and Ashe were both tried and reprieved on the same day supports the view that it was the effect of the executions on public opinion and the delay which saved them."

Almost always, treatment of de Valera's reprieve includes some reference to his American birth - if only to deny it.

But was de Valera accurate in saying his late court-martial helped save him? Probably so.

In the book WE Wylie and the Irish Revolution 1916-1921, León Ó Broin draws on Wylie's unpublished memoir about his service as a second lieutenant in the Territorial Army and as a barrister who witnessed many of the court-martial proceedings after the Rising.

On May 8, 1916, according to Wylie, the commander of the British forces, General Sir John Maxwell, showed him a telegram from H H Asquith, saying the British prime minister wanted the executions to end.

According to Ó Broin: "Maxwell asked Wylie who was next on his list for court-martial, no doubt wondering whether there was anyone on it likely to be executed."

"Somebody called de Valera, sir."

"Who is he?" said Maxwell. "I haven't heard of him before."

"He was in command of Boland's bakery in the Ringsend area."

"I wonder would he be likely to make trouble in the future?" Maxwell went on.

"I wouldn't think so, sir, I don't think he is important enough. From all I can hear, he is not one of the leaders."

"All right then," said the Commander-in-Chief.

Wylie went on to acknowledge that he "was far off the mark" in judging whether de Valera might cause "trouble in the future". An examination of Asquith's papers at Oxford University supports de Valera's basic premise that the lateness of his court-martial proved decisive to his commutation. Asquith's files about what is referred to in one document as "this most recent German campaign" provide the distinct impression that another front in the Great War had opened up in Ireland, and there are several tally reports about the number of people killed, wounded, taken prisoner - and executed.

De Valera's name does not appear in the dispatches sent to Asquith, even though his death sentence had been commuted.

The day after Maxwell reported to the prime minister that the court-martials were "practically finished", he reiterated - and defended - his position for the executions of James Connolly and Seán Mac Diarmada, both of whom were Proclamation signatories and major participants in the Rising.

Interestingly, Maxwell does not acknowledge de Valera's role as a commandant in his communiqués. Connolly and Mac Diarmada were the last two leaders executed on May 12. At the same time the final firing squads were being assembled, de Valera sat in his cell at Kilmainham Gaol, writing farewell letters to family and friends that included for some these chilling words: "Tomorrow I am to be shot."

But that tomorrow never came. De Valera escaped death and served time in British prisons before his release and the beginning of a political career that continued until 1973, when he left the presidency at age 90. Why did he wait so long to prepare his formal statement titled 'Reprieve of Éamon de Valera'? Had the repeated references to his American background become a distraction, if not a burden, for someone identified as the dominant Irish political figure of the 20th Century?

Especially during the period when de Valera was fighting for independence, it was valuable to keep the relationship to the US in the public's mind. When he landed in New York on June 11, 1919, for an 18-month sojourn in the States to build support for an Irish republic, Irish-Americans took pride in the fact that a native son was in a central position to try to do for Ireland what the colonies in the New World accomplished at the end of the 18th Century. The Yanks also reached into their wallets to help the cause de Valera championed, as he barnstormed across the country and spoke to massive crowds.

Clarifying the details of his reprieve could wait several decades while he cultivated the mystery of his persona - and made history.

Robert Schmuhl is professor of American Studies at the University of Notre Dame and the author of 'Ireland's Exiled Children: America and the Easter Rising', which will be published in March by Oxford University Press. This article is adapted from the chapter about de Valera

Nagging doubt about the timing of Rising

For someone who harboured serious misgiving about the planning for the Easter Rising, Éamon de Valera soldiered on and ultimately became a symbol and embodiment of its importance to the cause of Irish independence.

Interestingly, however, before the first shots were fired on April 24, 1916, de Valera could not envision how he would survive the rebellion's combat.

How concerned was this senior officer of the Irish Volunteers about his future? He made sure to prepare a will in advance of the fighting.

According to his authorised biography, Éamon de Valera, by the Earl of Longford and Thomas P O'Neill: "His position as an insurgent would not, he felt, invalidate the will, but he was anxious in regard to a small life assurance policy. If he were killed in the Rising, would the assurance company pay the sum assured? In fact, he felt that death was almost inevitable."

Then, after he surrendered and was arrested, he awaited death again, this time by firing squad at Kilmainham Gaol. Imagine what it was like, in terms of concentrating the mind, to compose a succession of farewell letters to family and friends telling them he'd be shot before long.

A year after the Rising, while imprisoned in Britain, de Valera wrote a letter to his wife, Sinéad. Both poignant and deeply personal, the words revisit the darkness he experienced earlier.

"Yes this time last year I foresaw for you the agonies you would suffer when the rifles began to crackle and the guns to boom almost at the door. I foresaw, and endured in sympathy the terrible suspense you would endure so long as the fighting continued or till you heard definitely of my death - I saw you finally sink stunned with the leaden weight of the last news - bereft of that last thread of hope which alone made the suspense bearable.

"Yet I did not foresee what was perhaps the most terrible part of all for you. The long interval from the surrender till the announcement of my sentence - made more terrible for you by the daily list of those condemned and executed, but during the time itself I knew you were suffering and I prayed God to lighten it."

Moving as the letter continues to be, it is one of the few autobiographical statements de Valera wrote about the Rising itself and his feelings related to it.

In his biography of Dev, De Valera: Long Fellow, Long Shadow, Tim Pat Coogan observes: "Probably the most telling comment on de Valera's behaviour during 1916 is his own silence. Amongst all the recollections contained in his own collection of papers, lovingly preserved over a long lifetime, there is no de Valera memoir of 1916."

Coogan judges it "a pity" that de Valera never composed a detailed remembrance of the period before, during and immediately after the Rising. That it is.

Clearly, though, the exhilaration of cheating death twice in less than three weeks - a story told again and again - would become high-octane political petrol during de Valera's next six decades.

Indo Review