The photo shows a barricade erected by the 18th Royal Irish regiment - many of them Dubliners - at the junction of Moore Street and Parnell Street.
The soldiers have their rifles pointed down Moore Street to a terrace of houses where the rebels had relocated after evacuating the GPO.
Volunteer Frank Burke recalled: "The military were entrenched behind a high barricade at the end of Moore Street."
His comrade James Kavanagh said: "I saw an old man come out of a shop... No sooner did he appear than a bullet from one of the 18th Royal Irish...struck him...he was mortally wounded."
This picture was possibly taken on Saturday April 29, 1916, the day of the rebels' surrender. Two hours before they did so, a white flag was taken by Elizabeth O'Farrell from rebel HQ to the barricade to seek terms.