English losses are given as roughly 400-600 men and two ships, against French losses of about 16,000-20,000 men and 190 ships, including 166 captured. Armor and heavy clothing made escape by water exceptionally difficult. The danger fell disproportionately on wealthier soldiers whose more extensive protection made swimming and surfacing harder. The French lost more men at Sluys than at Crécy and Agincourt combined, removing experienced soldiers whose absence shaped later English victories.
Chapter · 54:37-58:14
Sluys destroyed a fleet and a field army at once
French losses of roughly 16,000-20,000 men and 190 ships dwarfed the casualties of Crécy or Agincourt.