At about eight o'clock on the morning of Thursday 8 May 1902, the feast of the Ascension, Mount Pelée on the north of Martinique erupted and a burning cloud swept down on the port of Saint-Pierre, killing almost its entire population of some 28,000 people within minutes. Le Morne-Rouge lay on the volcano's slopes only five kilometres away. Its people, long devoted to the Sacred Heart, ran to the parish church of Notre-Dame de la Délivrande to beg Our Lady of Deliverance to spare them. The parish priest, Father Mary, gave general absolution to the crowd, distributed Holy Communion, and exposed the Blessed Sacrament on the altar for adoration.
During the exposition a woman cried out that the Sacred Heart of Jesus was in the Host. A great number of those present then reported seeing Jesus in the Host showing his Heart crowned with thorns, and some said they saw blood flowing from it. The vision lasted several hours and ended only when the monstrance was returned to the tabernacle. While Saint-Pierre burned, Morne-Rouge came through that day untouched, and the people took the apparition as a call to return to God.
The story does not end in deliverance, and the exhibition panel does not pretend otherwise. On 30 August 1902 another burning cloud from Pelée struck Morne-Rouge itself, killing about 1,500 people; Father Mary died helping those who had taken refuge in the church, which lost its roof and furnishings though the statue of Our Lady survived. The tradition reads the May vision as a respite granted so that the village could receive the sacraments and prepare. No formal ecclesiastical inquiry is recorded; the account rests on the testimony of the parishioners. The church was rebuilt between 1907 and 1912 and remains the island's principal Marian shrine.