Shrove Tuesday: the day when traditionally all fat and meat in the house were finished up, before Christians were banned from eating them during Lent, which commenced the following day on mercredi des Cendres; Mardi Gras: the last day of a carnival, traditionally the celebration immediately before the start of Lent when joy could be out of place for Christians; a person dressed up in a ridiculous disguise
“Lorsqu'il se vit à la tête d'une puissante armée, il laissa les François dans les Landes, & passant la montagne sur la fin du carnival de l'année 1566. il alla camper à Balagna le mardi gras: […]” — When he found himself at the head of a powerful army, he left the French in Landes, and crossing the mountain at the end of Carnival of the year 1566, he set camp in Balagna at Shrove Tuesday: […]
Literally, “fat Tuesday”.