The French camp is hit hard by an epidemic of dysentery on the heels of the naval loss.

Philip himself is afflicted.

The heir to the French throne, the future Philip IV, opens negotiations with Peter for free passage for the royal family through the Pyrenees,.

The pass around the massif of Albères (five hundred and sixty-eight meters) was the main route through the Pyrenees in Antiquity.

The Romans called it the Summum Pyrenæum.

It had since been superseded by the Col de Perthus one kilometer to the northeast.

The Aragonese troops, saving promised to leave the passage to the French king and his family, content themselves with attacking the retreating French army, decimated by dysentery.

Peter entrusts the vanguard to Ramon de Montcada and his Almogàvers, who massacre the fatigued French but spare the royal family.

This first attack is followed up by a second attack by Roger de Lauria, the admiral of the fleet which had defeated the French at Les Formigues and had then disembarked to fight on land.

The result of all this is a rout: the French are decimated further and it is a complete Aragonese victory.

According to the chronicle of Ramon Muntaner, the festivities of celebration last eight days in Barcelona.

The king of France himself dies on October 5 at Perpignan, the capital of James of Majorca, and is buried in …

…Narbonne.

The French soon experience a reversal, however, at the hands of Peter III's admiral, Roger de Lauria.

The French fleet is defeated and destroyed at the Battle of Les Formigues on September 4, 1285 .There are three almost completely different accounts of this battle in Ramon Muntaner, Bernard Desclot, and the Gesta comitum Barchinonensium.

The Gesta places the battle at Les Formigues (or Formigas), while Muntaner favors a location off Roses (Rosas) to the north.

Either Lauria or the French are ashore for the night and encountered by the other, or they are both at sea when the encounter takes place.

The accounts agree that it happened at night, which was unusual for medieval naval battles, but suited Lauria, who is skilled at night-fighting.

He uses two lanterns on each galley to increase his apparent numbers.

Ten to sixteen Genoese galleys under John de Orreo flee, leaving about fifteen to twenty French galleys to be captured, and some others sunk or burnt, which destroys for a long time the French naval power in the Mediterranean.

The troubadour Joan Esteve blames treachery for the capture of the French admiral Guilhem.

It is said that three hundred French prisoners were sent back to France.

All of the prisoners but one had their eyes gouged out, and that one was left with one eye to guide the others.

The prisoners brought one message from Roger of Lauria to the King of France: that not even fish would be able to navigate safely through Mediterranean Sea without a shield or sign of the king of Aragon on them.

The disease that had devastated the French ranks at Gerona also claims King Pedro (Peter) III of Aragon, who dies on the march home, at about forty-five, on November 11, 1285; he will be posthumously honored as Peter the Great.

The king’s oldest son becomes King Alfonso III of Aragon; his second son, James, becomes king of Sicily.