When I was 8 years old, I spend the summer with my grandparents, at their farmhouse. One evening, my grandmother gave me the Green Scapular and asked me to say the prayer "Immaculate Heart of Mary, pray for us, now and at the hour of our death" every evening before bed. I kept it next to my bed and said the prayer faithfully. I still have one today.
The scapular was given in 1840 by Our Lady to Sister Justine Bisqueyburu, a Daughter of Charity from the rue du Bac, Paris. She was an heiress who had consecrated her life early to the Immaculate Heart of Mary. During her noviciate, her spiritual director was Fr Aladel, who had also been the director of St. Catherine Laboure. At first, he didn't beleive in her revelations from Our Lady and forbid her to discuss it. It took many years of discernment for the scapular to be distributed. Sr. Justine trained as a nurse and was send to the Crimean war. She made such an impression on Florence Nightingale that the latter decided to base her new nursing order on the rule of the Daughters of Charity. Sr Justine also served in North Africa and found the way to stop cholera transmission among the patients and staff at her hospital. She was a confidente of Pius IX during his emprisonement at the Vatican. It is Pius IX who approved the scapular in 1870 as a sacramental of the Church.