The phrase that Morel coined to describe the alleged terror by Senegalese troops in the Rhineland was the "Black Horror on the Rhine", which became internationally famous, and the campaign against the "black horror" took much of his time for the last four years of his life. Morel predicated the "black horror" would cause another world war, writing that the average German boy was thinking: ""Boys these men raped your mothers and sisters"" (emphasis in the original). Morel used the "black horror" as a way of attacking France, which he claimed had caused a "sexual horror on the Rhine" and whose "reign of terror" was a “giant evil" that should inspire "shame into all four corners of the world" and ultimately should "a revision of the Versailles Treaty and the relief for Germany".