The English vessels attacked from windward, seizing Eustace's ship, making Robert and the knights prisoner and killing the rest of the crew.

The battle convinced Prince Louis to abandon his effort to conquer England and the Treaty of Lambeth was signed a few weeks later.

[2] After his lieutenants were badly defeated at the Battle of Lincoln on 20 May 1217, Prince Louis raised his siege of Dover Castle and retired to London.

Signalling his willingness to negotiate an end to the struggle, he agreed to meet at Brentford with adherents of the boy-king Henry III of England.

[7] Louis had been invited to land with troops in England by the English barons in revolt against the tyranny of King John and this was not a war of nations but of factions.

The English mariners complained bitterly of bad treatment at the hands of King John, but Pembroke convinced them to fight with the promise of great spoils should they defeat the French.

[11] All eleven troopships were overloaded, particularly the flagship which carried a large trebuchet and horses destined for Prince Louis.

[8] The English ships were generally smaller than the French, except for a substantial cog provided by the Earl of Pembroke, who was persuaded to stay ashore.

[12] 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.

[15] 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.

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.

[16] Marked for execution by the enraged English, Eustace was tied down and a man named Stephen Crabbe struck off his head with one blow.

[19] The French troopships owed their deliverance to their train of supply vessels because the English turned aside to plunder the smaller craft.

Prince Louis formally renounced his claims to the English crown in return for being allowed an unmolested departure from England.

In return for Henry III's pardon, the barons who had joined Louis were made to pay the French prince 10,000 marks to expedite his withdrawal.