‘They’ve sworn an oath to protect the cohort commander. If Cordus gets close to them, he might persuade them to back him, next time he tries to confront us.’

‘You think he will?’ Antonius asked.

‘If Caratacus doesn’t arrive by the time we’ve finished our defences, then the men will have time on their hands, and they’ll do what they normally do in such circumstances: talk. Given the presence of me and Macro, and the absence of Maximius, I should think we’ve given them plenty to talk about.’

Antonius looked down at his boots. ‘We’re fucked.’

‘Any way you look at it,’ Cato smiled. ‘Now, sir, the guards?’

‘You take them,’ Tullius said. ‘I don’t need them. Now you and your men had better get down that track.’

The Sixth Century trudged through the posts of the gateway. On either side legionaries paused to watch them as they passed, and then hurriedly returned to work as their officers screamed at them for stopping. Macro was standing on top of the rampart and waved briefly to Cato as he directed his men to start pounding in the stakes of wood they had brought from the fort to act as a makeshift palisade. The gateway was set back from the rest of the rampart, which angled in towards it, so that any attackers would be subjected to fire from three sides if they made any attempt to assault the gate. As his century marched out from the lines of defence, the ground on either side of the track gave way to patches of mud, then still expanses of dark water from which the pale yellow stalks of clumps of rushes rose up, their feathered heads hanging motionless in the hot still air.

When they reached the first bend in the track Cato stopped to look back at the rest of the cohort and marked the distance to the gateway. It was essential that he was familiar with the topography. If the enemy came upon them before they were recalled by Tullius, then Cato and his men would be making a fighting withdrawal. The weight of their armour and equipment made it impossible for them to outpace the enemy, who would be thirsting for Roman blood in any case. They would have a short head start on Caratacus and the Britons, and then the Sixth Century would have to fight nearly every step of the way back to the cohort frantically struggling to complete the defences. It would be a close thing - if they made it. But if their sacrifice bought Tullius and the others enough time to complete the defences, the Third Cohort might be able to hold off Caratacus and his force. Long enough, at least, for Vespasian to march across the marsh and close the trap on the enemy and crush them.