After the invasion by the Kingdom of France of the Duchy of Lorraine in 1632 under Cardinal Richelieu, Fourier refused to swear an oath of loyalty to King Louis XIII of France. Thus he and his community were forced to flee their monastery in 1636, taking refuge in the town of Gray in the neighboring County of Burgundy. Fourier and the canons with him were occupied in that city nursing plague victims. It was there that he died on 9 December 1640.