Coucy became Lord of Coucy at the death of his father, Enguerrand VI, Lord of Coucy, during the sequence of battles ending with the Battle of Crécy in 1346. He also gained the titles of 4th Lord Gynes, Sire d' Oisy, in the district of Marle, and the Sire de La Fère. His mother, Catherine of Austria, oldest daughter of Leopold I, Duke of Austria, had died in 1349, during a wave of the Black Death. Coucy first became involved in the war against England at the age of fifteen, serving among the barons of Picardy in the battalion of Moreau de Fiennes. In 1358, at the age of eighteen, Coucy acted as a leader during the suppression of the peasant revolt known as the Jacquerie.