Constance was committed for 'trial' - a brief court martial hearing - and initially lodged in Kilmainham jail, with her male co revolutionaries.
She was transferred from Kilmainham to Mountjoy jail, along with some twenty women and girls. She settled into prison life and in a letter to Eva assured her, humourously, that
"It is very economical living here. I feel half glad that I am not treated as a political prisoner, as I would then be tempted to eat, smoke and dress at my own expense…Everybody is quite kind and although this is not exactly a bed of roses, still many rebels have had much worse to bear. Life is colourless, the beds are hard, the food peculiar, but you might say that of many a free person’s life."
In June 1916 Constance was transported to England and imprisoned in Aylesbury jail, where she was to remain until June 1917.
Prisoner "G.12" at Aylesbury
She had had another letter smuggled out to Eva advising that she was going to Aylesbury jail, and continuing… "I shall be quite amiable…and I am not going to hunger strike as I am advised by comrades to do. It would suit the Government very well to let me die quietly…"
Constance had been sentenced to hard labour. Her rations were two ounces of cheese and a small piece of bread at 10pm each day; lunch at noon was on ounces of meat, two ounces of cabbage, one potato, thick flour gravy and six ounces of bread; varied on Thursdays when there was hard cold suet pudding with black treacle, and on Fridays when the prisoners ate boiled fish. Supper at 4:30 p.m. was a pint of cocoa or tea with six ounces of bread. Constance lost weight, dropping to seven and a half stone. She was shut in her cell for the night at 5:30 p.m.
Unlike others who had participated in the Rising, Constance was denied the company of colleagues. Her companions were female convicts, who were in general ignorant or uneducated. With much badgering her sister Eva persuaded the Home Office to allow Constance to paper and pencil for drawing. Constance was put to work in the sewing room where she made prison nightgowns and underwear from unbleached calico. She complained the work was too inactive, so she was assigned to cleaning the prison kitchens.
The conditions of her imprisonment proved the subject of controversy. In February 1917 the Irish Women’s International League petitioned the Home Secretary claiming that…
"The late Home Secretary had promised to accord to the Irish men and women imprisoned for participation in the Insurrection of last Eastr the privileges of political prisoners. We understood that such privileges would remove Madame de Markievicz from enforced association with criminals and would entitle her to advantages in the way of food, clothes and books. We learn, however, from her sister that she is still in a convict prison under the same discipline and treatment as the lowest type of criminals and is placed in close association with prostitutes of infamous character.
In the name of justice and humanity we feel compelled to protest against the infliction of this punishment upon a women whose motives were pure and whose moral character was unblemished, however serious her political offences…We therefore beg you to fulfil the promises already made to this prisoner and to grant her without further delay the ordinary privileges given to political prisoners…"
Constance’s time at Aylesbury was difficult. Her health suffered. Only with immense difficulty did Eva obtain a concession that her sister should have a glass of milk a day. Constance constantly complained of being hungry. Once she said to Miss Roper, "The only thing that prison does for people, as far as I can see, is to teach them to use bad language and to steal. I was so hungry yesterday I stole a raw turnip and ate it."
In writing of her experiences in jail in the San Francisco Examiner of December 1919, Constance recollected:
"The chief thing that strikes you…is the extreme dirt concealed under a parade of cleanliness. Every bit of brass is immaculate, the floors are scrubbed unceasingly, but the baths were constantly so dirty that we refused to use them until they were washed. Vermin was constantly crawling over one.
Every evening they served us out porridge with a huge tin ladle from a can, then the ladle was left for the night in a dirty pail with the brush which was used to sweep the lavatory…
The mattress I was given on my entry was so dirty that I cannot describe it. I had to put up with this until the very day I was released. I was given some old clothes which had been discarded by another convict who had left the prison. The shoes were full of holes, which let in the wet and snow.
There was one horror always hanging over our heads, and that was the fear of catching loathsome diseases. One section of the prison was called the Borstal and contained some one hundred and fifty "girls". We cooked and washed up for that number. The food was served in tins, many of them old and musty. The girls’ tins often came down to us in a state too disgusting to be described and there was neither sufficient water, vessels, or labour employed to keep them really clean…Fifteen tins were marked with a "D". We were told to keep them separate from the rest.
About fifteen more tins were marked. No care was taken outside the kitchen and they were always getting mixed up with the others in spite of our protestations, and shortly we were told that it did not matter and not to mind about separating them.
While I was there one of these "girls" tried to kill herself by cutting her throat; another set fire to her cell and she nearly died from burns. Several tried to hang themselves with ropes used in the making of mail bags and more swallowed buttons and huge needles. Poor girls! It seemed so wicked and futile to drive them to this."
Although she was still in prison in August 1915, Cumann Na mBann, elected her president at their annual convention.
Attitudes in Ireland were changing. AE had written a tribute to the rebels, printed for private circulation.