The castle at Auray guarded the bridge across the river that swept around the town, forming an island on three sides. From its heights defenders could see the town with its hospital and church and the busy narrow streets. Those who patrolled the ramparts felt safe looking across the rooftops to the distant plain. The tidal river dropped so low that body-swallowing mud would suck down any man stupid enough to wade across, and at high tide the town’s militia could easily kill men clambering from boats onto the quayside. The castle’s looming walls were too high for scaling ladders and the narrow strip of land between river and outer curtain walls made it impossible for siege towers to take up position. The ancient Dukes of Brittany knew how to build an impregnable castle. They could not know that a hundred years and more later an English King’s Master of War would study the great citadel and see how to breach its walls.

‘It cannot be done,’ said John de Montfort, who might be twenty-five years old but looked to have only recently crept into manhood. The contrast his youthful appearance made with the veteran fighting men was emphasized by his thin whiskers and drooping moustache. ‘Better that we ignore the town and seek out the enemy.’

When de Montfort turned away, Sir John Chandos glanced at Blackstone with a look that said: I told you so.

Blackstone remained silent as the impatient young man paced back and forth until he could no longer tolerate being ignored by his elders. ‘I have two thousand men. They have rallied to my cause. We must seize Brittany with honour in battle.’ He glared from one man to the other. ‘Answer me!’

‘My lord, you have not asked a question,’ said Blackstone.

‘Do not talk to me as if I were a child!’ said de Montfort.

‘I will not if you listen to those who know better. And if you do not then you will never gain the duchy, because you will be dead, consumed by maggots and forgotten by history.’ Blackstone’s measured tones struck de Montfort as hard as if he had clubbed him around the ear.

His jaw dropped. He stammered, looking from Blackstone to Chandos, eyes tear-filled as rage took hold. ‘Sir John! You bring this insolent knight into my quarters to humiliate me?’ He faced Blackstone. ‘Get out!’

Blackstone didn’t move. De Montfort pointed a trembling finger at him. ‘His insolence offends me.’

‘And at times it offends the Prince – and many others – but Sir Thomas is honoured and trusted and you would be wise to listen to him,’ said Chandos.

De Montfort bleated. ‘It is I who command here with you at my side.’