There are some unsolved mysteries from Easter 1916 that historians still argue about today - and probably always will. Here are five of the most contentious questions.
1. Were the rebels planning to make a German prince King of Ireland?
The Proclamation declared an 'Irish Republic', but it may not have been a republic as we understand it today.
During Easter Week in the GPO, Patrick Pearse and Joseph Plunkett were heard discussing this very issue - apparently suggesting that Germany's Prince Joachim (son of Kaiser Wilhelm II) might be offered the throne of an independent Ireland.
Joachim ended up shooting himself in 1920, apparently unaware of any plan.
Another disputed question is which of the Proclamation's signatories was supposed to be in charge afterwards. Tom Clarke's widow Kathleen was furious that Pearse would have been head of the government, complaining that he "knew as much about commanding as my dog".
2. Did the Pope have advance knowledge of the Rising?
George Noble Plunkett, a papal count and father of Joseph, had a private audience with Pope Benedict XV in Rome two weeks before the Rising.
According to him, he told the Pope about what was being planned in Dublin. Benedict reportedly cried, "Those poor men!" and gave the rebels his blessing.
Most historians find this hard to believe, since the Papacy was neutral during World War I and the Rising was a blow against the British Empire. But did Count Plunkett lie or was something lost in translation? Is the answer awaiting discovery in a Vatican filing cabinet?
3. Who wrote the 'Castle Document'?
On the Wednesday before the Rising, a sensational document was read out at a meeting of Dublin Corporation. It had allegedly come from Dublin Castle and contained plans to arrest the Volunteer leaders as well as other prominent nationalists.
Eoin MacNeill, the Volunteers' chief-of-staff, at first thought this was justification for a rebellion and declared: "The Lord has delivered them into our hands!"
By the weekend, however, he had decided that the document was a forgery by the Irish Republican Brotherhood.
Was MacNeill right? Sean McDermott swore to a priest shortly before his execution that the document had been real, while Joseph Plunkett's fiancée Grace remembered sitting on his bed while he deciphered it with a codebook.
One possible theory is that Plunkett 'sexed up' an original document to make the threat seem more immediate than it really was - but nobody will ever know for sure.
4. Why did the rebels not seize Dublin Castle?
As the headquarters of British rule in Ireland, Dublin Castle was an obvious target.
It was also extremely vulnerable on Easter Monday, since almost everyone had gone to the races at Fairyhouse and only 25 soldiers were on duty.
Thirty Irish Citizen Army members marched to the Castle and shot an unarmed policeman outside. After entering the courtyard, however, they seemed to have no idea what to do and quickly retreated inside City Hall next door.
Whatever the reason, this was typical of a rebellion that seemed more interested in dramatic gestures than practical achievements.
5. How did Eamon de Valera escape the firing squad?
The future Taoiseach and President was condemned to die and wrote farewell letters to his closest friends.
In the end, however, his sentence was commuted to life imprisonment - even though as commandant at Boland's Mill he had been more senior than many rebels who were shot.
For a long time, the standard explanation was that New York-born Dev cheated death because he was an American citizen and Britain needed US support in the First World War. This was certainly what de Valera told a fascinated President John F Kennedy in 1963.
However, being a US citizen did not do Tom Clarke any good, and Dev himself admitted in private notes that there must have been another reason.
The truth was probably more simple. By the time de Valera's turn came, Britain had started to realise that the executions were having a terrible effect on public opinion. Also, General Maxwell made inquiries and became convinced that Dev was just an obscure maths teacher.
So he became the great survivor of 1916 - which from Britain's point of view was probably their biggest mistake.