Teresa Ellen Dease

Teresa Ellen Dease (4 May 1820 – 1 July 1889) was a Roman Catholic nun and the foundress of the Loreto Sisters (Institute of the Blessed Virgin Mary in Canada and in North America. She arrived in Toronto in 1847 at the invitation of Bishop Michael Power.

Life Ellen Dease was born in Naas, County Kildare, Ireland, the youngest of five children born to Oliver and Anne Nugent Dease. Her father was a surgeon at Westmoreland Lock Hospital. Orphaned at a young age, she was raised by her maternal grandmother in Dublin, where she attended a school for young ladies. In January 1847 Bishop Michael Power of Toronto went on a six-month visit to Europe, seeking to recruit additional priests and to raise money for his cathedral. While in Ireland he arranged for the Sisters of Loreto to establish a mission in Toronto. Dease was asked if she would take part.

Canada Dease professed her vows on 3 August 1847 and two days later set out for Canada with four other sisters. They arrived in Toronto 16 September 1847 in the midst of a typhus epidemic. Power contracted the illness while tending the sick and died 1 October. The sisters rented a house on Duke Street and began to give lessons in languages and music. The following year, they moved to a larger house and began a boarding school. Income from the boarder and day students helped to finance a free school for the poor of the cathedral parish.

Unused to Canadian winters, Sister Gertrude (Mary) Fleming had had a foot amputated due to frostbite; the founding superior, Mother Ignatius Hutchinson died. Within four years of arrival, Dease was the only member of the initial group still alive in Canada. In March 1851, Dease was named superior. She wrote Mother Frances Ball suggesting that the mission be closed and they return home. Mother Francis directed them to stay. A few sisters arrived from Ireland and more homegrown vocations developed. By 1859, thirty-one members had joined the community. Although initially reluctant, she changed the curriculum to align with that of the provincial schools to better prepare the students for professional careers. To ensure the sisters were fully qualified to teach, by 1870 they began to attend Normal School.

In 1881, the Vatican made the North American branch of the Institute a separate generalate and Mother Dease became its first Superior General.

Dease is buried at the former Loretto convent in Niagara Falls, Ontario.