On 24 August, in clear weather, the French fleet set out from Calais. Though the ships were equipped by Eustace the Monk, command of the knights and soldiers was held by Robert of Courtenay. The wife of Prince Louis,
Blanche of Castile was also an important organizer of the relief effort. Opposing the French was
Philip d'Aubigny, commander of the southeastern coast. Eustace's own vessel, the
Great Ship of Bayonne led the French squadron. Robert de Courtenay held the top command while Eustace served as his deputy. Ralph de la Tourniele and William des Barres were third and fourth in command, respectively. All told, there were 36
knights on the flagship. The next three troopships were commanded by Mikius de
Harnes, William V of
Saint-Omer, and the Mayor of
Boulogne. Altogether, the first four ships, including the flagship, contained between 100 and 125 knights.
Men-at-arms manned the remaining six troopships. There were 70 smaller vessels which carried supplies. All eleven troopships were overloaded, particularly the flagship which carried a large
trebuchet and horses destined for Prince Louis. As
justiciar, Hubert de Burgh claimed leadership of the fleet, which has sometimes led to him being included anachronistically on lists of the
lord high admirals. All told there were no more than 40 English ships, 1618 larger ships and 20 smaller vessels. King John's illegitimate son
Richard FitzRoy commanded one ship. The English, who had recovered Sandwich from Louis' forces, determined to let the French armada pass by before attacking. When the French sailed past Sandwich, de Burgh's fleet issued from the port. Aided by their upwind position, the English archers inflicted considerable damage on the enemy sailors and soldiers before the French bowmen were able to effectively reply. The English also opened pots of lime which blew in the faces of the French. Early in the battle, the French flagship engaged Richard FitzRoy's ship. As more English ships came up, they joined the fight against the flagship, while the other French ships maintained their tight formation, but failed to assist their flagship. Pembroke's cog and FitzRoy's ship grappled Eustace's flagship, one on each side. After a one-sided melee, Robert of Courtenay and the French knights were captured for ransom, while the French sailors and common soldiers were massacred. Eustace, dragged from his hiding place in the bilge, offered to pay 10,000
marks as ransom. Though his very high price was tempting, FitzRoy and the other English leaders considered Eustace a turncoat because of the pirate's employment by King John. With their flagship taken, the French fleet headed back to Calais. Encouraged, the English attacked, using ramming, grappling, and rigging-cutting to disable the enemy vessels. The nine surviving troopships got away, but most of the smaller vessels fell prey to the English mariners. As few as 15 ships escaped from the rampaging English. The French troopships owed their deliverance to their train of supply vessels because the English turned aside to plunder the smaller craft. ==Result==