Mary McMahon was born on 25 May 1879 in Dungannon, Tyrone, the daughter of Mary and Owen. She had four brothers and one sister. Also known as Minnie. She became a nun with the “Little Sisters of the Poor”.
Mary joined the Order of St Joseph in the United States as Sister Jessie. She was based in Oklahoma and in a letter dated March, 1919, she mentions being in correspondence with her brother George – back from the war – and her sister in the French convent. She also mentions a brother called Owen who clearly died young.