William sent an army to relieve Saint-Omer but was defeated at the village of Zuytpeene just to the west of Cassel, losing 7-8,000 men killed or wounded and another 4,000 taken prisoner.
William enviou um exército para apoiar Saint-Omer, mas foi derrotado na aldeia de Zuytpeene, imediatamente a oeste de Cassel, perdendo 7 a 8 mil homens, feridos ou mortos, e outros 4 mil prisioneiros.