Secret police files which provide a remarkable insight into the run-up to the 1916 Rising are now available to the public online.
They show how some of those suspected of being involved in nationalist activities at the time were closely monitored by the British authorities.
Online access to the files is part of the National Archives contribution to the Ireland 2016 Centenary Programme.
They contain what was at the time highly secretive material, collated in a series of daily reports, by the detective section of the Dublin Metropolitan Police.
"These files begin at the start of June in 1915, and lead right up to April 20, 1916, just four days before the beginning of the 1916 Rising," said Minister for Arts, Culture, and the Gaeltacht, Heather Humphreys.
"They describe Republican activity in Dublin at the time, and include details of intelligence gathered at a number of key city centre locations, such as the shop of Thomas J Clarke at 75 Parnell Street, and the Irish Volunteers Office on Dawson Street.
"The files may be 100 years old, but they still paint a fascinating picture of how the Dublin Metropolitan Police were monitoring the people who they believed were plotting Ireland's independence.
"More than 230 individuals were monitored, with a number of very familiar names cropping up in the files.
"These include Thomas J Clarke, who is mentioned in almost every report, Con Colbert, Seán T Ó Ceallaigh, Seán Mac Diarmada," said the Minister, who launched the new service.
"Major events which took place in 1915 and 1916 were also under close surveillance."
The files include references to the funeral of Jeremiah O'Donovan Rossa and the Annual Convention of the Irish Volunteers.
"The reports also include details of anti-recruitment and-conscription rallies and meetings of the Irish Women's Franchise League. There is much fascinating material about the period.
"I am delighted to see the National Archives making these files available online, which will ensure they are accessible to the greatest possible audience.
"This is one of a number of digitisation projects taking place as part of Ireland 2016,'' she added.
John McDonough, director of the National Archives, said staff at the archives are pleased to be able to share this important collection.
"The weekly release of this material will allow visitors to our website to track the movements of those involved in the Rising in the months leading up to April 1916.
"People will be able to read how key players were identified, followed, and put under surveillance, and read the thoughts of the detectives tracking them."
The reports were compiled by Superintendent Owen Brien and submitted to the Under Secretary for Ireland, Sir Matthew Nathan, at Dublin Castle.
They describe Republican activity in Dublin during the 11 months preceding the Easter Rising.
The individuals referred to in the reports are, principally, members of the Irish Volunteers, the Irish Republican Brotherhood and Sinn Féin.
In total, there were approximately 260 files comprising 700 documents, which were conserved, listed and scanned.
The reports will be released on the website of the National Archives on a weekly basis as from today.
Updates will also be available on the National Archives Twitter account @narireland, which goes live as from tomorrow.
The reports can be accessed at www.nationalarchives.ie.
The National Archives hold the records of the modern Irish State, which document its historical evolution.