Philip vacillated: on the day the siege of Calais began he disbanded most of his army, to save money and convinced that Edward had finished his chevauchée and would proceed to Flanders and ship his army home.
On or shortly after 7 September, Duke John made contact with Philip, having shortly before disbanded his own army.
On 9 September Philip announced that the army would reassemble at Compiègne on 1 October, an impossibly short interval, and then march to the relief of Calais.
Among other consequences, this equivocation allowed Lancaster in the south west to launch offensives into Quercy and the Bazadais; and himself lead a chevauchée 160 miles (260 km) north through Saintonge, Aunis and Poitou, capturing numerous towns, castles and smaller fortified places and storming the rich city of Poitiers.
These offensives completely disrupted the French defences and shifted the focus of the fighting from the heart of Gascony to 60 miles (97 km) or more beyond its borders.
Few French troops had arrived at Compiègne by 1 October and as Philip and his court waited for the numbers to swell, news of Lancaster's conquests came in.
Believing that Lancaster was heading for Paris, the French changed the assembly point for any men not already committed to Compiègne to Orléans, and reinforced them with some of those already mustered, to block this.
After Lancaster turned south to head back to Gascony, those Frenchmen already at or heading towards Orléans were redirected to Compiègne; French planning collapsed into chaos.

Philip had been calling on the Scots to fulfil their obligation under the terms of the Auld Alliance and invade England since June.
The Scottish king, David II, convinced that English force was focused entirely on France, obliged on 7 October.
He was brought to battle at Neville's Cross on 17 October by a smaller English force raised exclusively from the northern English counties.
The battle ended with the rout of the Scots, the capture of their king and the death or capture of most of their leadership.
Strategically this freed significant English resources for the war against France, and the English border counties were able to guard against the remaining Scottish threat from their own resources.

Even though only 3,000 men-at-arms had assembled at Compiègne, the French treasurer was unable to pay them.
Philip cancelled all offensive arrangements on 27 October and dispersed his army.
Recriminations were rife: officials at all levels of the Chambre des Comptes (the French treasury) were dismissed and all financial affairs were put into the hands of a committee of three senior abbots.
The King's council bent their efforts to blaming each other for the kingdom's misfortunes.
Philip's heir, Duke John, fell out with his father and refused to attend court for several months.
Joan II, Queen of Navarre, daughter of a previous king of France (Louis X), and previously a partisan of Philip, declared neutrality and signed a private truce with Lancaster.
Philip vacillated: on the day the siege of Calais began he disbanded most of his army, to save money and convinced that Edward had finished his chevauchée and would proceed to Flanders and ship his army home. On or shortly after 7 September, Duke John made contact with Philip, having shortly before disbanded his own army. On 9 September Philip announced that the army would reassemble at Compiègne on 1 October, an impossibly short interval, and then march to the relief of Calais. Among other consequences, this equivocation allowed Lancaster in the south west to launch offensives into Quercy and the Bazadais; and himself lead a chevauchée 160 miles (260 km) north through Saintonge, Aunis and Poitou, capturing numerous towns, castles and smaller fortified places and storming the rich city of Poitiers. These offensives completely disrupted the French defences and shifted the focus of the fighting from the heart of Gascony to 60 miles (97 km) or more beyond its borders. Few French troops had arrived at Compiègne by 1 October and as Philip and his court waited for the numbers to swell, news of Lancaster's conquests came in. Believing that Lancaster was heading for Paris, the French changed the assembly point for any men not already committed to Compiègne to Orléans, and reinforced them with some of those already mustered, to block this. After Lancaster turned south to head back to Gascony, those Frenchmen already at or heading towards Orléans were redirected to Compiègne; French planning collapsed into chaos.
Philip had been calling on the Scots to fulfil their obligation under the terms of the Auld Alliance and invade England since June. The Scottish king, David II, convinced that English force was focused entirely on France, obliged on 7 October. He was brought to battle at Neville's Cross on 17 October by a smaller English force raised exclusively from the northern English counties. The battle ended with the rout of the Scots, the capture of their king and the death or capture of most of their leadership. Strategically this freed significant English resources for the war against France, and the English border counties were able to guard against the remaining Scottish threat from their own resources.
Even though only 3,000 men-at-arms had assembled at Compiègne, the French treasurer was unable to pay them. Philip cancelled all offensive arrangements on 27 October and dispersed his army. Recriminations were rife: officials at all levels of the Chambre des Comptes (the French treasury) were dismissed and all financial affairs were put into the hands of a committee of three senior abbots. The King's council bent their efforts to blaming each other for the kingdom's misfortunes. Philip's heir, Duke John, fell out with his father and refused to attend court for several months. Joan II, Queen of Navarre, daughter of a previous king of France (Louis X), and previously a partisan of Philip, declared neutrality and signed a private truce with Lancaster.
Crécy campaign