In the 17th century, the plague raged in Lyon. Faced with this scourge, on September 8, 1643, feast of the Nativity of the Virgin, the provost of merchants (equivalent to the mayor) and his 4 aldermen (deputies), accompanied by a crowd of Lyonnais, went in procession to Fourvière.
It is in the Chapel of the Virgin that they vow to go up every year to hear mass, to offer 7 pounds of white wax and a gold shield, if Lyon is spared. Soon after, the evil recedes and their wish is granted.
Since that date, every September 8, the mayor of Lyon and elected officials go up to Fourvière to perpetuate this commitment and the Archbishop blesses the city with the Blessed Sacrament. Three cannon shots announce this blessing. The renewal of the Vow of the Aldermen demonstrates Lyon's attachment to the Virgin, protector of the city.
The celebration of September 8 is this year chaired by Monsignor Michel Dubost, apostolic administrator of the diocese and in the presence of elected officials of the city, except the new mayor Gregory Doucet who gave a conference outside the religious building.