In the Spring of 1843 some local people and clergy came together in the Parish School at the corner of Stanhope Street and Stanhope Place to discuss the possibility of bringing the Sisters of Mercy to Athy. The first Sisters of Mercy had been professed 12 years earlier and already a Convent had been established in the neighbouring town of Carlow. Those who played a large part in organising that meeting were Miss Anna Gould of Stanhope Place, Rev. W. Gaffney C.C., the Fitzgerald family of Geraldine House and Patrick Maher of Kilrush. It was agreed to take up a weekly collection in the town of Athy to finance the building of a Convent for the Sisters of Mercy. By the 12th of May, 1843 £150 had been collected but an approach to the Duke of Leinster for a site was unsuccessful. Undaunted the fund raising continued and in August 1844 the Parish Priest of Castledermot, Rev. Laurence Dunne, laid the first stone of the future Convent on marshy ground to the west of the Parish Church.
The building work continued throughout 1845 and 1846 but stopped in 1847 because of lack of funds. The weekly town collection was not taken up during the Great Famine, but restarted in 1848, this time under the direction of Rev. Thomas Greene C.C. in whose memory a beautiful Celtic Cross was many years later erected in the grounds of St. Michael’s Parish Church.
Dr. Paul Cullen, appointed Archbishop of Dublin in 1852, was born in Prospect in the Parish of Narraghmore in the year of Robert Emmet’s Rebellion. Understandably he took a keen personal interest in the completion of the Convent in the South Kildare town of Athy, which was located just six miles from his ancestral home. Mother Mary Vincent Whitty of the Sisters of Mercy Dublin advanced £300 to the local people to have the building completed and on 10th October, 1852 Mother Vincent, who earlier had been responsible for building the Mater Hospital, Dublin, took charge of the new Convent accompanied by two sisters. They remained in Athy for two years after which time the Sisters of Mercy in Carlow took over the Athy Convent as a branch house and sent Sister Mary Teresa Maher and Sister Mary Xavier Downey in their place. Sister Mary O'Grady Dillon and Sister Mary Joseph later joined them from the Baggot Street Convent.
Sister Mary Teresa Maher was daughter of Patrick Maher of Kilrush who was one of those responsible for bringing the Sisters of Mercy to Athy. She was also a first cousin of Archbishop Cullen. Sister Mary Vincent Whitty who opened the Athy Convent in October 1852 was the first Sister of Mercy to go on missionary work to Australia where she was later to be joined by a number of nuns and postulants from the Athy Convent.
In 1861 an appeal was made by Rev. Andrew Quinn P.P., Athy, to Rev. Mother Teresa Maher on behalf of his brothers Rt. Rev. James Quinn, Bishop of Brisbane and Rt. Rev. Matthew Quinn, Bishop of Bathurst, Australia, for nuns for their respective missions. In 1865 a postulant from Athy’s Convent, Catherine Flanagan, travelled to Brisbane and in the following year four more postulants left the local Convent in Athy for the Australian Missions. One of the many nuns and postulants who left Athy for Queensland was Sr. Mary Patrick Potter who entered the Athy Convent on the 8th of June, 1866. She and four others left for Brisbane on the 26th of February, 1868. They were the last Athy nuns to leave Athy for Australia. By then Athy had become known as the Mother House of Queensland, having sent so many Mercy Sisters and postulants to that Province over the years.
In 1879 Mother Mary Patrick Potter was appointed Superior of the Congregation in Brisbane, a position she held until her death in 1927. She established many convents and schools throughout Queensland while the building of the Mater Hospital in Brisbane was another of her many achievements.
Over the 140 years of their life in Athy the Sisters of Mercy have worked amongst the people, providing help where required and responding to the spiritual, educational and sometimes material needs of the people of the area.