Battle of Damme
Summary
On May 30, 1213, Philip II Augustus sent a fleet from Gravelines to strike the transports that John Lackland had gathered at Damme. The French ships, led by Eustace the Monk and supported by the troops of William des Roches and Robert de Courtenay landed on the quays, surprised the English garrison. Within hours, nearly four hundred cargo ships were captured or burned, ruining invasion preparations.
Historical context
After having rallied the Emperor Otto IV and several Flemish princes, John Lackland prepared a descent into Flanders to take Philip from behind. He amassed ships and supplies in Damme, the port of Bruges controlled by his allies. Philippe, informed by Flemish merchants favorable to France, decided to strike preventively: he set sail his royal fleet reinforced by Dieppe corsairs and by Norman sailors who remained loyal to the Capetian crown.
Tactics
The French combined a naval raid and a land attack: Eustace the Monk led a first wave of light galleys which cut the moorings, while boarding parties seized the ships one after the other. William des Roches landed knights and sergeants who set fire to the stranded buildings and repelled the Flemish reinforcements. The English, surprised without sailors on board, could not form a line of defense and abandoned the port.
Consequences
The destruction of the fleet forced John to abandon the invasion of 1213 and deprived Otto IV of essential logistical support. Philip can concentrate his forces on the land campaign of 1214 which ends at Bouvines. French control of the Channel also strengthened the maritime economy of Dieppe and the Picardy ports, while England had to rebuild its fleet at great expense.