Catherine de Longpré was raised by her grandparents in Normandy after the death of her parents and entered the Augustinian Hospitallers of the Mercy of Jesus at Bayeux at thirteen in 1645 — taking the religious name Catherine of Saint Augustine. In 1648, at sixteen, she volunteered for the new mission of the Augustinian Hospitallers to Quebec, where the Duchesse d'Aiguillon had founded the Hôtel-Dieu in 1639 as the first hospital in North America.
She sailed for Quebec in May 1648 and arrived in August. She served at the Hôtel-Dieu for the remaining twenty years of her life — through epidemics, indigenous warfare (she nursed Iroquois warriors and Huron refugees side-by-side during the 1649–50 catastrophe), the long Iroquois siege of Quebec, and the slow recovery of the colony.
Her mystical life — recorded in extraordinary detail in her own diary at the request of her spiritual director Father Paul Ragueneau (formerly superior of the Huron mission) — was an intense and unusual one. She believed herself in continuing struggle with demonic forces in the colony, and especially with the influence of an apostate Quebec priest. She received frequent visions of the recently-martyred Jean de Brébeuf — whom she had never met physically but who became her acknowledged mystical guide in the colony. The Brébeuf-Catherine connection is one of the foundational mystical episodes of Canadian Catholic spirituality. She died at the Hôtel-Dieu on May 8, 1668. Beatified by John Paul II in 1989.