On 30 May 1213, an English fleet commanded by William Longespée ⓘ, 3rd Earl of Salisbury launched a surprise attack on a large French invasion fleet assembled at Damme in Flanders by Philip II of France ⓘ.

King John ⓘ had taken the offensive in response to preparations for a French invasion of England. The English forces burned and captured a substantial number of French transport ships and supply vessels in the harbour. The destruction of the fleet disrupted Philip’s immediate invasion plans and secured England against attack.

Although the wider conflict between England and France continued, the victory at Damme temporarily restored English naval dominance in the Channel and marked one of the few clear military successes of John’s reign before the reverses that culminated in the campaign of 1214 and the crisis of Magna Carta.