After the Bruges Matins, de Coninck was one of the leaders of the Bruges militia that cleared the coastal area from "Leliaart" insurgents and French stragglers. After they failed to take the besieged castle of Cassel, they marched onto Kortrijk (Courtrai) where a Flemish makeshift army was gathering to stop a French army under the command of Robert II of Artois. This battle, won by a motley alliance of Flemish and Namur petty nobles and many commoners, was later famously called the Battle of the Golden Spurs.