Hanna was introduced to Francis Skeffington by mutual friend James Joyce, who went to university with Skeffington.
The couple would meet regularly in Bewley's Cafe to discuss politics, the arts and religion.
Hanna married Francis Skeffington on June 3, 1903 at University Chapel in St. Stephen's Green, Dublin. The couple wore their graduation gowns as a substitute for a traditional wedding gown and suit.They jointly adopted the surname "Sheehy Skeffington".
Together Hanna and Francis joined the Irish Women's Suffrage and Local Government Association, and the Young Ireland Branch of the United Irish League (the constituency element of the Irish Parliamentary Party). They also supported the Women's Social and Political Union, which lobbied for women's rights in Britain. Shortly after they married, Francis organised a petition to lobby for women to be admitted to University College on the same basis as men. When the university refused to take that step, Francis resigned from his job as registrar in protest, relying on Hanna to support him for a time.
In 1912 he co-founded the Irish Women's Franchise League with his wife Hanna, and was made co-editor of the League's newspaper, The Irish Citizen.
In 1909 Francis and Hanna had a son, Owen. They were much criticized for refusing to have him baptized.
At the outset of the Easter Rising, Sheehy Skeffington opposed the violent methods of the insurgents, advocating a nonviolent form of civil disobedience, while his wife Hanna actively sympathized with the insurgents and joined the group of women who brought food to those stationed at the General Post Office and the Royal College of Surgeons. In contrast, on the first day of the rising (Monday 24 April 1916) Francis risked crossfire to go to the aid of an English soldier outside Dublin Castle. As Hanna recalled the incident six years later: "When the outbreak began on Easter Monday my husband was near Dublin Castle. He learned that a British officer had been gravely wounded and was bleeding to death on the cobblestones outside the Castle gate. My husband persuaded a bystander to go with him to the rescue. Together they ran across the square under a hail of fire. Before they reached the spot, however, some British troops rushed out and dragged the wounded man to cover inside the gate."
On 25 April, Sheehy Skeffington went back into the city centre and, again according to Hanna, "actively interested himself in preventing looting". He returned to the GPO, emerging around one o'clock, and began to walk around the area. busied himself visiting various people, including priests, to enlist their help in guarding specific shops. That afternoon he had tea with his wife Hanna in one of the tea shops which, astonishingly, were still open in the city centre. Hanna then returned home to mind their child Owen, and Francis went to his meeting. Unfortunately the meeting was poorly attended, and no one volunteered to help Francis stop the looting.
On his way home from the dispiriting meeting, Francis was followed by a crowd of hecklers who were shouting out his nickname, "Skeffy!" This crowd of hecklers turned out to be a crucial cog in the machinery of fate which was to bring on his death. Undoubtedly they were the very inner city poor whom he had been exhorting to refrain from looting - and who would have been familiar with him from his many impromptu speeches on the steps of the Custom House, where he exhorted the passers-by on feminist or socialist subjects. He lived at that time at 11 (now 21) Grosvenor Place in Rathmines, and as he and his hecklers approached the Portobello Bridge, around 7:30 p.m., they were intercepted by soldiers of the 11th East Surrey Regiment. The officer in charge was under orders to keep the road and bridge clear, and felt apprehensive about the disorderly crowd. He detained Sheehy Skeffington, who said that he was "not a Sinn Féiner", but admitted to sympathy for the insurgents' cause, though he was opposed to violence. He was then arrested and brought back to the Portobello Barracks in Rathmines (now the Cathal Brugha Barracks).
Towards 11pm that evening an officer of the 3rd battalion of Royal Irish Rifles, Captain John C. Bowen-Colthurst, took Sheehy Skeffington back out of the barracks, as a hostage in a raiding party. The raid was aimed at the tobacconist shop of Alderman James Kelly, a moderate "home rule" nationalist, whom Bowen-Colthurst had mistaken for a separatist of the same name, Alderman Tom Kelly.
The raiding party, consisting of 25 men led by Bowen-Colthurst, along with Sheehy Skeffington who was held with his hands tied behind his back, left the barracks and headed towards Rathmines Road, where they intercepted two young men who were returning from a meeting of a religious sodality. On the pretext of the lateness of the hour, Bowen-Colthurst detained and threatened them, eventually shooting one of them: a 19-year-old mechanic named James Coade, who was left in the road and subsequently died of his wound. Sheehy Skeffington witnessed this and protested against the shooting as the raiding party made its way through Rathmines. The party continued on down Lower Rathmines Road, and the soldiers stopped at the Portobello Bridge, where half of the men were left at a guardhouse along with Sheehy Skeffington. Bowen-Colthurst gave orders that the soldiers at the guardhouse were to monitor the further progress of the raiding party, and shoot Sheehy Skeffington if either his or their party came under attack from snipers. He also ordered Sheehy Skeffington to say his last prayers in case this were to happen, and when Sheehy Skeffington refused, Bowen-Colthurst said prayers on his behalf.
The raiding party continued on to the shop of Alderman James Kelly, 300 yards away at the corner of Camden Street and Harcourt Road (now known as "Kelly's Corner"). Having heard gunshots which they presumed to be emanating from Kelly's shop, the soldiers destroyed the shop (which was also Kelly's home) with hand grenades. They also captured two men who had taken refuge in the shop, Thomas Dickson and Patrick MacIntyre, both pro-British journalists.
That night, Bowen-Colthurst was up much of the night praying and reading the Bible. On the following morning, he ordered the two journalists and Sheehy Skeffington taken out to a yard in the barracks, where he intended to have them shot. He told a subordinate officer this was "the best thing to do". In the yard he assembled a squad of seven men and ordered them to fire immediately at the three prisoners, who until that moment were not aware they were about to die. After killing the three men, the firing squad immediately left the yard, but when movement was detected in Sheehy Skeffington's leg, Bowen-Colthurst gathered another group of four soldiers and ordered them to fire another volley into him. Bowen-Colthurst later reported what he had done to his superior, Major Rosborough; he said he took responsibility for the shooting and that he "possibly might be hanged for it". Rosborough asked him for a written report, and Colthurst was confined to barracks duties. The bodies were hastily buried in the grounds.
The man in overall charge of defence at Portobello Barracks was 55-year-old Sir Francis Vane (1861-1934), a Dublin-born major in the Royal Munster Fusiliers. Vane was not present when these shootings took place, having taken up an observation post at the top of the nearby Rathmines Town Hall. Later on Wednesday morning, when Vane returned to the compound, he heard what had happened during his absence from a young lieutenant attached to the Army Service Corps who was stationed at the barracks. Vane was horrified and went immediately to see the deputy commander of the garrison, Major Rosborough. He told Rosborough he believed that Bowen-Colthurst was mentally deranged. Rosborough then ordered a subordinate to telephone the garrison high command, and also to make an exceptional telephone report to the British high command at Dublin Castle. The garrison high command replied with an order to bury the bodies in the barracks yard. This was done after Roman Catholic rites had been performed by a chaplain. At a later date the bodies were exhumed in the presence of Sheehy Skeffington's father, and then reburied in consecrated ground.
In an interview with the playwright Hayden Talbot six years after the killing, Hanna said her husband's body "had been put in a sack and buried in the barracks' yard. The remains were given to his father on condition that the funeral would be at early morn and that I be not notified. My husband's father consented unwillingly to do this on the assurance of General Maxwell that obedience would result in the trial and punishment of the murderer." Re-interment took place on 8 May 1916 at Glasnevin Cemetery.
Hanna Sheehy Skeffington was not told about her husband's detention or his death. She went around Dublin seeking to find where her husband was, and heard rumours of his fate. Her two sisters then offered to visit Portobello Barracks on Friday and make inquiries. Upon revealing their business, the two sisters were arrested as "Sinn Féiners", and questioned by Captain Bowen-Colthurst. Bowen-Colthurst denied any knowledge as to the fate of Francis Sheehy Skeffington, and had them released. Later on Friday Hanna learned the dreadful news from the father of the young boy Coade who had also been shot, and the news was confirmed to her by the chaplain who had performed the funerary rites, and who also worked in the neighborhood.
On that same Friday evening, Bowen-Colthurst and a group of soldiers forced entry into the Sheehy Skeffingtons' home, hoping to find evidence to incriminate Francis as an enemy sympathiser. Hanna, Owen (then seven), and a "young maid-servant" were in the house, where Owen was just being put to bed. The soldiers announced their presence by firing a volley of bullets through the front windows. The soldiers then burst in through the front door, wielding rifles with fixed bayonets, and ordered the three residents to stand under guard while they searched the premises. According to an official report, "All the rooms in the house were thoroughly ransacked and a considerable quantity of books and papers were wrapped up in the household linen, placed in a passing motor car, and taken away. ... A large part of the material removed seems to have consisted of text-books both in German and other languages, as well as political papers and pamphlets belonging to Mr. Sheehy Skeffington." The maid-servant, terrified by the experience, subsequently quit her job. She was replaced by another maid who was subsequently arrested and detained for four days after another raid by the Portobello garrison (this time not ordered by Bowen-Colthurst). But upon examination several months later by a government commission, none of the material was found to be seditious.
Hanna Sheehy Skeffington was offered financial compensation by the British government in 1916, but she refused it because it came on the condition that she cease to speak and write about the murder. She became increasingly nationalist-minded, and supported the anti-Treaty side in the Irish Civil War. She refused to send her son Owen to any school with a pro-Treaty ethos, and therefore opted to place him in the secular Sandford Park School when it was founded in 1922. Her sister's son Conor Cruise O'Brien was also placed there. Hanna died in 1946.