Harriet Starr Cannon founded the Community of St. Mary. Cannon was born in Charleston in 1823 and was orphaned in 1824 when her parents died of yellow fever. She grew up with her only surviving sibling in Bridgeport, Connecticut, in the home of relatives. In 1851, Cannon entered the Sisters of the Holy Communion, an order founded by William Augustus Muhlenberg, Rector of the Church of the Holy Communion in New York City. The Sisters were heavily involved in the operation of clinics and care facilities that would become St. Lukes Hospital in the City of New York. During her years with the Sisters of the Holy Communion, Cannon served as a nurse.