France’s defeat by Prussia in 1870-1871 left a bitter taste in the country. In January 1871, Alexandre Legentil (1821-1889) and his brother-in-law Hubert Rohault de Fleury (1828-1910) wrote an exhortation to ask Jesus for forgiveness for the country’s faults and pledged to contribute to the erection of a sanctuary in Paris dedicated to the Heart of Jesus. A law of public utility was passed in 1873 to allow developers to acquire the land at the top of the Butte Montmartre. This was the beginning of the great adventure of the Sacré-Coeur thanks to the wish of two men.