 Although St. Cecilia's was still only a priory, Cécile Bruyère was named abbess of the new foundation at the age of 24 by Pope Pius IX on 20 June 1870.This may have been a gesture of thanks towards Dom Guéranger for his great support to the Pope at the First Vatican Council in favour of the recently proclaimed dogma of Papal infallibility.Mother Cécile, with the support of Dom Guéranger, wrote the nunnery's constitutions, which were influential beyond her own nunnery.